21115670724 has 36 divisors (see below), whose sum is σ = 53459051100. Its totient is φ = 7027568640.

The previous prime is 21115670707. The next prime is 21115670761. The reversal of 21115670724 is 42707651112.

21115670724 is a `hidden beast` number, since 21 + 1 + 1 + 567 + 0 + 72 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 11338416324 + 9777254400 = 106482^2 + 98880^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 434449 + ... + 480600.

Almost surely, 2^21115670724 is an apocalyptic number.

It is an amenable number.

21115670724 is an abundant number, since it is smaller than the sum of its proper divisors (32343380376).

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

21115670724 is a wasteful number, since it uses less digits than its factorization.

21115670724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 915700 (or 915695 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The spelling of 21115670724 in words is "twenty-one billion, one hundred fifteen million, six hundred seventy thousand, seven hundred twenty-four".