20971597 has 4 divisors (see below), whose sum is σ = 21004956. Its totient is φ = 20938240.

The previous prime is 20971583. The next prime is 20971619. The reversal of 20971597 is 79517902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79517902 = 2 ⋅39758951.

It can be written as a sum of positive squares in 2 ways, for example, as 19105641 + 1865956 = 4371^2 + 1366^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20971597 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 (20971507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15718 + ... + 16999.

It is an arithmetic number, because the mean of its divisors is an integer number (5251239).

Almost surely, 2^20971597 is an apocalyptic number.

It is an amenable number.

20971597 is a deficient number, since it is larger than the sum of its proper divisors (33359).

20971597 is an equidigital number, since it uses as much as digits as its factorization.

20971597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33358.

The product of its (nonzero) digits is 39690, while the sum is 40.

The square root of 20971597 is about 4579.4756250034. The cubic root of 20971597 is about 275.7679778307.

The spelling of 20971597 in words is "twenty million, nine hundred seventy-one thousand, five hundred ninety-seven".