21472642656 has 72 divisors (see below), whose sum is σ = 61190700480. Its totient is φ = 7142558976.

The previous prime is 21472642613. The next prime is 21472642679. The reversal of 21472642656 is 65624627412.

21472642656 is a `hidden beast` number, since 214 + 7 + 2 + 6 + 426 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×21472642656² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60126 + ... + 215778.

It is an arithmetic number, because the mean of its divisors is an integer number (849870840).

Almost surely, 2^21472642656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21472642656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30595350240).

21472642656 is an abundant number, since it is smaller than the sum of its proper divisors (39718057824).

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

21472642656 is a wasteful number, since it uses less digits than its factorization.

21472642656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156148 (or 156137 counting only the distinct ones).

The product of its digits is 967680, while the sum is 45.

It can be divided in two parts, 21472 and 642656, that added together give a triangular number (664128 = T₁₁₅₂).

The spelling of 21472642656 in words is "twenty-one billion, four hundred seventy-two million, six hundred forty-two thousand, six hundred fifty-six".