21137331 has 4 divisors (see below), whose sum is σ = 28183112. Its totient is φ = 14091552.

The previous prime is 21137327. The next prime is 21137353. The reversal of 21137331 is 13373112.

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

It is not a de Polignac number, because 21137331 - 2² = 21137327 is a prime.

It is a super-2 number, since 2×21137331² = 893573523607122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21137298 and 21137307.

It is not an unprimeable number, because it can be changed into a prime (21137371) 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, 3522886 + ... + 3522891.

It is an arithmetic number, because the mean of its divisors is an integer number (7045778).

Almost surely, 2^21137331 is an apocalyptic number.

21137331 is a deficient number, since it is larger than the sum of its proper divisors (7045781).

21137331 is an equidigital number, since it uses as much as digits as its factorization.

21137331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7045780.

The product of its digits is 378, while the sum is 21.

The square root of 21137331 is about 4597.5353179720. The cubic root of 21137331 is about 276.4925174583.

The spelling of 21137331 in words is "twenty-one million, one hundred thirty-seven thousand, three hundred thirty-one".