21661121612 has 48 divisors (see below), whose sum is σ = 42407971200. Its totient is φ = 9612153600.

The previous prime is 21661121609. The next prime is 21661121737. The reversal of 21661121612 is 21612116612.

It is a Harshad number since it is a multiple of its sum of digits (29).

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, 330362 + ... + 390462.

It is an arithmetic number, because the mean of its divisors is an integer number (883499400).

Almost surely, 2^21661121612 is an apocalyptic number.

It is an amenable number.

21661121612 is a deficient number, since it is larger than the sum of its proper divisors (20746849588).

21661121612 is a wasteful number, since it uses less digits than its factorization.

21661121612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60386 (or 60384 counting only the distinct ones).

The product of its digits is 1728, while the sum is 29.

The spelling of 21661121612 in words is "twenty-one billion, six hundred sixty-one million, one hundred twenty-one thousand, six hundred twelve".