21039081 has 24 divisors (see below), whose sum is σ = 34555680. Its totient is φ = 11313792.

The previous prime is 21039079. The next prime is 21039091. The reversal of 21039081 is 18093012.

It is not a de Polignac number, because 21039081 - 2¹ = 21039079 is a prime.

It is a super-2 number, since 2×21039081² = 885285858649122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21039001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1711 + ... + 6708.

It is an arithmetic number, because the mean of its divisors is an integer number (1439820).

Almost surely, 2^21039081 is an apocalyptic number.

21039081 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21039081 is a deficient number, since it is larger than the sum of its proper divisors (13516599).

21039081 is a wasteful number, since it uses less digits than its factorization.

21039081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8453 (or 8446 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21039081 is about 4586.8377996175. The cubic root of 21039081 is about 276.0634568437.

The spelling of 21039081 in words is "twenty-one million, thirty-nine thousand, eighty-one".