Base | Representation |
---|---|
bin | 101000010110… |
… | …1011100110001 |
3 | 1110210220212211 |
4 | 1100231130301 |
5 | 20404021211 |
6 | 2033252121 |
7 | 344560126 |
oct | 120553461 |
9 | 43726784 |
10 | 21157681 |
11 | 10a41096 |
12 | 7104041 |
13 | 44ca34c |
14 | 2b4a74d |
15 | 1ccde21 |
hex | 142d731 |
21157681 has 8 divisors (see below), whose sum is σ = 21738528. Its totient is φ = 20580000.
The previous prime is 21157649. The next prime is 21157693. The reversal of 21157681 is 18675112.
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 21157681 - 25 = 21157649 is a prime.
It is a super-2 number, since 2×211576812 = 895294930595522, which contains 22 as substring.
It is not an unprimeable number, because it can be changed into a prime (21157601) 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, 19606 + ... + 20656.
It is an arithmetic number, because the mean of its divisors is an integer number (2717316).
Almost surely, 221157681 is an apocalyptic number.
It is an amenable number.
21157681 is a deficient number, since it is larger than the sum of its proper divisors (580847).
21157681 is a wasteful number, since it uses less digits than its factorization.
21157681 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1583.
The product of its digits is 3360, while the sum is 31.
The square root of 21157681 is about 4599.7479278760. The cubic root of 21157681 is about 276.5812202060.
The spelling of 21157681 in words is "twenty-one million, one hundred fifty-seven thousand, six hundred eighty-one".
• e-mail: info -at- numbersaplenty.com • Privacy notice • done in 0.218 sec. • engine limits •