21552291 has 16 divisors (see below), whose sum is σ = 32533920. Its totient is φ = 14096160.

The previous prime is 21552283. The next prime is 21552317. The reversal of 21552291 is 19225512.

21552291 is a `hidden beast` number, since 21 + 552 + 2 + 91 = 666.

It is not a de Polignac number, because 21552291 - 2³ = 21552283 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21552221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6100 + ... + 8961.

It is an arithmetic number, because the mean of its divisors is an integer number (2033370).

Almost surely, 2^21552291 is an apocalyptic number.

21552291 is a deficient number, since it is larger than the sum of its proper divisors (10981629).

21552291 is a wasteful number, since it uses less digits than its factorization.

21552291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15123 (or 15117 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 21552291 is about 4642.4445069381. Note that the first 3 decimals coincide. The cubic root of 21552291 is about 278.2901366822.

The spelling of 21552291 in words is "twenty-one million, five hundred fifty-two thousand, two hundred ninety-one".