21020331 has 32 divisors (see below), whose sum is σ = 30481920. Its totient is φ = 12857600.

The previous prime is 21020303. The next prime is 21020339. The reversal of 21020331 is 13302012.

It is a happy number.

It is not a de Polignac number, because 21020331 - 2⁵ = 21020299 is a prime.

It is a super-2 number, since 2×21020331² = 883708630699122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21020339) 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 31 ways as a sum of consecutive naturals, for example, 253216 + ... + 253298.

It is an arithmetic number, because the mean of its divisors is an integer number (952560).

Almost surely, 2^21020331 is an apocalyptic number.

21020331 is a deficient number, since it is larger than the sum of its proper divisors (9461589).

21020331 is a wasteful number, since it uses less digits than its factorization.

21020331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21020331 is about 4584.7934522724. The cubic root of 21020331 is about 275.9814233454.

Adding to 21020331 its reverse (13302012), we get a palindrome (34322343).

The spelling of 21020331 in words is "twenty-one million, twenty thousand, three hundred thirty-one".