21511648612 has 6 divisors (see below), whose sum is σ = 37645385078. Its totient is φ = 10755824304.

The previous prime is 21511648607. The next prime is 21511648643. The reversal of 21511648612 is 21684611512.

It can be written as a sum of positive squares in only one way, i.e., 19178372196 + 2333276416 = 138486^2 + 48304^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2688956073 + ... + 2688956080.

Almost surely, 2^21511648612 is an apocalyptic number.

It is an amenable number.

21511648612 is a deficient number, since it is larger than the sum of its proper divisors (16133736466).

21511648612 is a wasteful number, since it uses less digits than its factorization.

21511648612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5377912157 (or 5377912155 counting only the distinct ones).

The product of its digits is 23040, while the sum is 37.

The spelling of 21511648612 in words is "twenty-one billion, five hundred eleven million, six hundred forty-eight thousand, six hundred twelve".