21951988605 has 80 divisors (see below), whose sum is σ = 39728392704. Its totient is φ = 11596037760.

The previous prime is 21951988571. The next prime is 21951988621. The reversal of 21951988605 is 50688915912.

21951988605 is a `hidden beast` number, since 2 + 19 + 5 + 19 + 8 + 8 + 605 = 666.

It is not a de Polignac number, because 21951988605 - 2⁷ = 21951988477 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 25436404 + ... + 25437266.

Almost surely, 2^21951988605 is an apocalyptic number.

It is an amenable number.

21951988605 is a deficient number, since it is larger than the sum of its proper divisors (17776404099).

21951988605 is a wasteful number, since it uses less digits than its factorization.

21951988605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1408 (or 1399 counting only the distinct ones).

The product of its (nonzero) digits is 1555200, while the sum is 54.

The spelling of 21951988605 in words is "twenty-one billion, nine hundred fifty-one million, nine hundred eighty-eight thousand, six hundred five".