21318597 has 6 divisors (see below), whose sum is σ = 30793542. Its totient is φ = 14212392.

The previous prime is 21318541. The next prime is 21318599. The reversal of 21318597 is 79581312.

It can be written as a sum of positive squares in only one way, i.e., 15163236 + 6155361 = 3894^2 + 2481^2 .

It is not a de Polignac number, because 21318597 - 2⁶ = 21318533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21318599) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1184358 + ... + 1184375.

It is an arithmetic number, because the mean of its divisors is an integer number (5132257).

Almost surely, 2^21318597 is an apocalyptic number.

It is an amenable number.

21318597 is a deficient number, since it is larger than the sum of its proper divisors (9474945).

21318597 is a wasteful number, since it uses less digits than its factorization.

21318597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2368739 (or 2368736 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 21318597 is about 4617.2066230568. The cubic root of 21318597 is about 277.2806350126.

The spelling of 21318597 in words is "twenty-one million, three hundred eighteen thousand, five hundred ninety-seven".