21306156021 has 24 divisors (see below), whose sum is σ = 31298938944. Its totient is φ = 13964486400.

The previous prime is 21306156013. The next prime is 21306156031. The reversal of 21306156021 is 12065160312.

21306156021 is a `hidden beast` number, since 21 + 3 + 0 + 61 + 560 + 21 = 666.

It is not a de Polignac number, because 21306156021 - 2³ = 21306156013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21306156031) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51010 + ... + 212636.

It is an arithmetic number, because the mean of its divisors is an integer number (1304122456).

Almost surely, 2^21306156021 is an apocalyptic number.

It is an amenable number.

21306156021 is a deficient number, since it is larger than the sum of its proper divisors (9992782923).

21306156021 is a wasteful number, since it uses less digits than its factorization.

21306156021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161881 (or 161878 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The spelling of 21306156021 in words is "twenty-one billion, three hundred six million, one hundred fifty-six thousand, twenty-one".