21974137 has 4 divisors (see below), whose sum is σ = 22346640. Its totient is φ = 21601636.

The previous prime is 21974119. The next prime is 21974179. The reversal of 21974137 is 73147912.

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 21974137 - 2¹¹ = 21972089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21974107) 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, 186163 + ... + 186280.

It is an arithmetic number, because the mean of its divisors is an integer number (5586660).

Almost surely, 2^21974137 is an apocalyptic number.

It is an amenable number.

21974137 is a deficient number, since it is larger than the sum of its proper divisors (372503).

21974137 is an equidigital number, since it uses as much as digits as its factorization.

21974137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372502.

The product of its digits is 10584, while the sum is 34.

The square root of 21974137 is about 4687.6579440057. The cubic root of 21974137 is about 280.0940882780.

The spelling of 21974137 in words is "twenty-one million, nine hundred seventy-four thousand, one hundred thirty-seven".