21360591 has 40 divisors (see below), whose sum is σ = 36927264. Its totient is φ = 12052800.

The previous prime is 21360589. The next prime is 21360593. The reversal of 21360591 is 19506312.

21360591 is a `hidden beast` number, since 2 + 13 + 60 + 591 = 666.

It is an interprime number because it is at equal distance from previous prime (21360589) and next prime (21360593).

It is not a de Polignac number, because 21360591 - 2¹ = 21360589 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21360593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 57081 + ... + 57453.

Almost surely, 2^21360591 is an apocalyptic number.

21360591 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21360591 is a deficient number, since it is larger than the sum of its proper divisors (15566673).

21360591 is a wasteful number, since it uses less digits than its factorization.

21360591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493 (or 484 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21360591 is about 4621.7519405524. The cubic root of 21360591 is about 277.4625807835.

The spelling of 21360591 in words is "twenty-one million, three hundred sixty thousand, five hundred ninety-one".