21065670556 has 18 divisors (see below), whose sum is σ = 42883686888. Its totient is φ = 9028144440.

The previous prime is 21065670551. The next prime is 21065670569. The reversal of 21065670556 is 65507656012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065670551) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 53738760 + ... + 53739151.

Almost surely, 2^21065670556 is an apocalyptic number.

It is an amenable number.

21065670556 is an abundant number, since it is smaller than the sum of its proper divisors (21818016332).

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

21065670556 is a wasteful number, since it uses less digits than its factorization.

21065670556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107477929 (or 107477920 counting only the distinct ones).

The product of its (nonzero) digits is 378000, while the sum is 43.

The spelling of 21065670556 in words is "twenty-one billion, sixty-five million, six hundred seventy thousand, five hundred fifty-six".