21131297 has 4 divisors (see below), whose sum is σ = 23052336. Its totient is φ = 19210260.

The previous prime is 21131293. The next prime is 21131317. The reversal of 21131297 is 79213112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21131297 - 2² = 21131293 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21131293) 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, 960503 + ... + 960524.

It is an arithmetic number, because the mean of its divisors is an integer number (5763084).

Almost surely, 2^21131297 is an apocalyptic number.

It is an amenable number.

21131297 is a deficient number, since it is larger than the sum of its proper divisors (1921039).

21131297 is a wasteful number, since it uses less digits than its factorization.

21131297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1921038.

The product of its digits is 756, while the sum is 26.

The square root of 21131297 is about 4596.8790499642. The cubic root of 21131297 is about 276.4662051702.

The spelling of 21131297 in words is "twenty-one million, one hundred thirty-one thousand, two hundred ninety-seven".