21215667372 has 12 divisors (see below), whose sum is σ = 49503223896. Its totient is φ = 7071889120.

The previous prime is 21215667313. The next prime is 21215667391. The reversal of 21215667372 is 27376651212.

It is a tau number, because it is divible by the number of its divisors (12).

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, 883986129 + ... + 883986152.

It is an arithmetic number, because the mean of its divisors is an integer number (4125268658).

Almost surely, 2^21215667372 is an apocalyptic number.

It is an amenable number.

21215667372 is an abundant number, since it is smaller than the sum of its proper divisors (28287556524).

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

21215667372 is a wasteful number, since it uses less digits than its factorization.

21215667372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1767972288 (or 1767972286 counting only the distinct ones).

The product of its digits is 211680, while the sum is 42.

The spelling of 21215667372 in words is "twenty-one billion, two hundred fifteen million, six hundred sixty-seven thousand, three hundred seventy-two".