1221010021 has 8 divisors (see below), whose sum is σ = 1522298304. Its totient is φ = 951436320.

The previous prime is 1221010019. The next prime is 1221010033. The reversal of 1221010021 is 1200101221.

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 1221010021 - 2¹ = 1221010019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221010081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7928560 + ... + 7928713.

It is an arithmetic number, because the mean of its divisors is an integer number (190287288).

Almost surely, 2^1221010021 is an apocalyptic number.

1221010021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221010021 is a deficient number, since it is larger than the sum of its proper divisors (301288283).

1221010021 is a wasteful number, since it uses less digits than its factorization.

1221010021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15857291.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1221010021 is about 34942.9538104608. The cubic root of 1221010021 is about 1068.8245224371.

Adding to 1221010021 its reverse (1200101221), we get a palindrome (2421111242).

The spelling of 1221010021 in words is "one billion, two hundred twenty-one million, ten thousand, twenty-one".