21089481 has 16 divisors (see below), whose sum is σ = 32578944. Its totient is φ = 11885184.

The previous prime is 21089477. The next prime is 21089489. The reversal of 21089481 is 18498012.

It is not a de Polignac number, because 21089481 - 2² = 21089477 is a prime.

It is a super-2 number, since 2×21089481² = 889532417698722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21089489) 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 15 ways as a sum of consecutive naturals, for example, 5346 + ... + 8411.

It is an arithmetic number, because the mean of its divisors is an integer number (2036184).

Almost surely, 2^21089481 is an apocalyptic number.

21089481 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21089481 is a deficient number, since it is larger than the sum of its proper divisors (11489463).

21089481 is a wasteful number, since it uses less digits than its factorization.

21089481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13840.

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 21089481 is about 4592.3284943479. The cubic root of 21089481 is about 276.2837215784.

The spelling of 21089481 in words is "twenty-one million, eighty-nine thousand, four hundred eighty-one".