21312985 has 8 divisors (see below), whose sum is σ = 27080136. Its totient is φ = 16047360.

The previous prime is 21312979. The next prime is 21313001. The reversal of 21312985 is 58921312.

It can be written as a sum of positive squares in 4 ways, for example, as 5184729 + 16128256 = 2277^2 + 4016^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21312985 - 2¹¹ = 21310937 is a prime.

It is a super-2 number, since 2×21312985² = 908486659220450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 125286 + ... + 125455.

It is an arithmetic number, because the mean of its divisors is an integer number (3385017).

Almost surely, 2^21312985 is an apocalyptic number.

It is an amenable number.

21312985 is a deficient number, since it is larger than the sum of its proper divisors (5767151).

21312985 is a wasteful number, since it uses less digits than its factorization.

21312985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250763.

The product of its digits is 4320, while the sum is 31.

The square root of 21312985 is about 4616.5988563010. The cubic root of 21312985 is about 277.2563020247.

The spelling of 21312985 in words is "twenty-one million, three hundred twelve thousand, nine hundred eighty-five".