21256506707 has 8 divisors (see below), whose sum is σ = 21457629600. Its totient is φ = 21055495104.

The previous prime is 21256506641. The next prime is 21256506829. The reversal of 21256506707 is 70760565212.

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 21256506707 - 2³⁰ = 20182764883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21256506407) 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, 384719 + ... + 436487.

It is an arithmetic number, because the mean of its divisors is an integer number (2682203700).

Almost surely, 2^21256506707 is an apocalyptic number.

21256506707 is a deficient number, since it is larger than the sum of its proper divisors (201122893).

21256506707 is a wasteful number, since it uses less digits than its factorization.

21256506707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55645.

The product of its (nonzero) digits is 176400, while the sum is 41.

The spelling of 21256506707 in words is "twenty-one billion, two hundred fifty-six million, five hundred six thousand, seven hundred seven".