21995137 has 4 divisors (see below), whose sum is σ = 22753620. Its totient is φ = 21236656.

The previous prime is 21995123. The next prime is 21995143. The reversal of 21995137 is 73159912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6948496 + 15046641 = 2636^2 + 3879^2 .

It is a cyclic number.

It is not a de Polignac number, because 21995137 - 2²³ = 13606529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21995096 and 21995105.

It is not an unprimeable number, because it can be changed into a prime (21995167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 379198 + ... + 379255.

It is an arithmetic number, because the mean of its divisors is an integer number (5688405).

Almost surely, 2^21995137 is an apocalyptic number.

It is an amenable number.

21995137 is a deficient number, since it is larger than the sum of its proper divisors (758483).

21995137 is an equidigital number, since it uses as much as digits as its factorization.

21995137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758482.

The product of its digits is 17010, while the sum is 37.

The square root of 21995137 is about 4689.8973336311. The cubic root of 21995137 is about 280.1832856089.

The spelling of 21995137 in words is "twenty-one million, nine hundred ninety-five thousand, one hundred thirty-seven".