21256920939 has 8 divisors (see below), whose sum is σ = 28350932992. Its totient is φ = 14167094760.

The previous prime is 21256920929. The next prime is 21256920941. The reversal of 21256920939 is 93902965212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21256920939 - 2¹⁷ = 21256789867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21256920929) 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, 1034599 + ... + 1054944.

It is an arithmetic number, because the mean of its divisors is an integer number (3543866624).

Almost surely, 2^21256920939 is an apocalyptic number.

21256920939 is a deficient number, since it is larger than the sum of its proper divisors (7094012053).

21256920939 is a wasteful number, since it uses less digits than its factorization.

21256920939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2092937.

The product of its (nonzero) digits is 524880, while the sum is 48.

The spelling of 21256920939 in words is "twenty-one billion, two hundred fifty-six million, nine hundred twenty thousand, nine hundred thirty-nine".