21937197 has 4 divisors (see below), whose sum is σ = 29249600. Its totient is φ = 14624796.

The previous prime is 21937187. The next prime is 21937213. The reversal of 21937197 is 79173912.

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 not a de Polignac number, because 21937197 - 2⁶ = 21937133 is a prime.

It is a super-2 number, since 2×21937197² = 962481224433618, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21937117) 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, 3656197 + ... + 3656202.

It is an arithmetic number, because the mean of its divisors is an integer number (7312400).

Almost surely, 2^21937197 is an apocalyptic number.

It is an amenable number.

21937197 is a deficient number, since it is larger than the sum of its proper divisors (7312403).

21937197 is an equidigital number, since it uses as much as digits as its factorization.

21937197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7312402.

The product of its digits is 23814, while the sum is 39.

The square root of 21937197 is about 4683.7161528000. The cubic root of 21937197 is about 279.9370479224.

The spelling of 21937197 in words is "twenty-one million, nine hundred thirty-seven thousand, one hundred ninety-seven".