21192561 has 24 divisors (see below), whose sum is σ = 34035456. Its totient is φ = 12618720.

The previous prime is 21192553. The next prime is 21192583. The reversal of 21192561 is 16529112.

21192561 is a `hidden beast` number, since 2 + 11 + 92 + 561 = 666.

It is not a de Polignac number, because 21192561 - 2³ = 21192553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21192511) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 706 + ... + 6548.

It is an arithmetic number, because the mean of its divisors is an integer number (1418144).

Almost surely, 2^21192561 is an apocalyptic number.

It is an amenable number.

21192561 is a deficient number, since it is larger than the sum of its proper divisors (12842895).

21192561 is a wasteful number, since it uses less digits than its factorization.

21192561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5893 (or 5890 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21192561 is about 4603.5378786320. The cubic root of 21192561 is about 276.7331249518.

The spelling of 21192561 in words is "twenty-one million, one hundred ninety-two thousand, five hundred sixty-one".