21311597 has 8 divisors (see below), whose sum is σ = 22495200. Its totient is φ = 20134224.

The previous prime is 21311527. The next prime is 21311599. The reversal of 21311597 is 79511312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21311597 - 2²⁰ = 20263021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311599) 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 7 ways as a sum of consecutive naturals, for example, 6623 + ... + 9299.

It is an arithmetic number, because the mean of its divisors is an integer number (2811900).

Almost surely, 2^21311597 is an apocalyptic number.

It is an amenable number.

21311597 is a deficient number, since it is larger than the sum of its proper divisors (1183603).

21311597 is a wasteful number, since it uses less digits than its factorization.

21311597 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3115.

The product of its digits is 1890, while the sum is 29.

The square root of 21311597 is about 4616.4485267357. The cubic root of 21311597 is about 277.2502831572.

The spelling of 21311597 in words is "twenty-one million, three hundred eleven thousand, five hundred ninety-seven".