21981504 has 28 divisors (see below), whose sum is σ = 58159904. Its totient is φ = 7327104.

The previous prime is 21981497. The next prime is 21981559. The reversal of 21981504 is 40518912.

It is a happy number.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 57052 + ... + 57435.

Almost surely, 2^21981504 is an apocalyptic number.

21981504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21981504 is an abundant number, since it is smaller than the sum of its proper divisors (36178400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21981504 is a wasteful number, since it uses less digits than its factorization.

21981504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114502 (or 114492 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 21981504 is about 4688.4436650129. The cubic root of 21981504 is about 280.1253860197.

The spelling of 21981504 in words is "twenty-one million, nine hundred eighty-one thousand, five hundred four".