309805812 has 36 divisors (see below), whose sum is σ = 784944160. Its totient is φ = 103028112.

The previous prime is 309805777. The next prime is 309805823. The reversal of 309805812 is 218508903.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×309805812² = 191959282297958688, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6003 + ... + 25605.

Almost surely, 2^309805812 is an apocalyptic number.

It is an amenable number.

309805812 is an abundant number, since it is smaller than the sum of its proper divisors (475138348).

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

309805812 is a wasteful number, since it uses less digits than its factorization.

309805812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20052 (or 20047 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 309805812 is about 17601.3014291557. The cubic root of 309805812 is about 676.6485990414.

The spelling of 309805812 in words is "three hundred nine million, eight hundred five thousand, eight hundred twelve".