Base | Representation |
---|---|
bin | 100100011001011… |
… | …0110101101000101 |
3 | 10011010002000001101 |
4 | 1020302312231011 |
5 | 10000122301241 |
6 | 321104300101 |
7 | 42156541432 |
oct | 11062665505 |
9 | 3133060041 |
10 | 1221290821 |
11 | 577428963 |
12 | 2a1011631 |
13 | 16603a2ba |
14 | b82b2b89 |
15 | 72343e31 |
hex | 48cb6b45 |
1221290821 has 8 divisors (see below), whose sum is σ = 1271590488. Its totient is φ = 1171968000.
The previous prime is 1221290767. The next prime is 1221290839. The reversal of 1221290821 is 1280921221.
It can be written as a sum of positive squares in 4 ways, for example, as 1185921 + 1220104900 = 1089^2 + 34930^2 .
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 1221290821 - 217 = 1221159749 is a prime.
It is a Duffinian number.
It is a self number, because there is not a number n which added to its sum of digits gives 1221290821.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1221290621) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 241660 + ... + 246661.
It is an arithmetic number, because the mean of its divisors is an integer number (158948811).
Almost surely, 21221290821 is an apocalyptic number.
It is an amenable number.
1221290821 is a deficient number, since it is larger than the sum of its proper divisors (50299667).
1221290821 is an equidigital number, since it uses as much as digits as its factorization.
1221290821 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 488423.
The product of its (nonzero) digits is 1152, while the sum is 28.
The square root of 1221290821 is about 34946.9715569175. The cubic root of 1221290821 is about 1068.9064499443.
The spelling of 1221290821 in words is "one billion, two hundred twenty-one million, two hundred ninety thousand, eight hundred twenty-one".
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