21372291 has 6 divisors (see below), whose sum is σ = 30871100. Its totient is φ = 14248188.

The previous prime is 21372289. The next prime is 21372293. The reversal of 21372291 is 19227312.

21372291 is a `hidden beast` number, since 2 + 1 + 372 + 291 = 666.

It is an interprime number because it is at equal distance from previous prime (21372289) and next prime (21372293).

It is not a de Polignac number, because 21372291 - 2¹ = 21372289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21372293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1187341 + ... + 1187358.

Almost surely, 2^21372291 is an apocalyptic number.

21372291 is a deficient number, since it is larger than the sum of its proper divisors (9498809).

21372291 is a wasteful number, since it uses less digits than its factorization.

21372291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2374705 (or 2374702 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21372291 is about 4623.0175210570. The cubic root of 21372291 is about 277.5132304381.

The spelling of 21372291 in words is "twenty-one million, three hundred seventy-two thousand, two hundred ninety-one".