21978906552 has 64 divisors (see below), whose sum is σ = 64643853600. Its totient is φ = 6895342080.

The previous prime is 21978906539. The next prime is 21978906571. The reversal of 21978906552 is 25560987912.

21978906552 is a `hidden beast` number, since 2 + 1 + 9 + 7 + 89 + 0 + 6 + 552 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2989099 + ... + 2996442.

Almost surely, 2^21978906552 is an apocalyptic number.

It is an amenable number.

21978906552 is an abundant number, since it is smaller than the sum of its proper divisors (42664947048).

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

21978906552 is a wasteful number, since it uses less digits than its factorization.

21978906552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5985573 (or 5985563 counting only the distinct ones).

The product of its (nonzero) digits is 2721600, while the sum is 54.

The spelling of 21978906552 in words is "twenty-one billion, nine hundred seventy-eight million, nine hundred six thousand, five hundred fifty-two".