21506672745456 has 20 divisors (see below), whose sum is σ = 55558904592552. Its totient is φ = 7168890915136.

The previous prime is 21506672745433. The next prime is 21506672745499. The reversal of 21506672745456 is 65454727660512.

It is a super-3 number, since 3×21506672745456³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21506672745456.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224027841051 + ... + 224027841146.

Almost surely, 2^{21506672745456} is an apocalyptic number.

It is an amenable number.

21506672745456 is an abundant number, since it is smaller than the sum of its proper divisors (34052231847096).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21506672745456 is a wasteful number, since it uses less digits than its factorization.

21506672745456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448055682208 (or 448055682202 counting only the distinct ones).

The product of its (nonzero) digits is 84672000, while the sum is 60.

The spelling of 21506672745456 in words is "twenty-one trillion, five hundred six billion, six hundred seventy-two million, seven hundred forty-five thousand, four hundred fifty-six".