309968640 has 144 divisors (see below), whose sum is σ = 1100080800. Its totient is φ = 82649088.

The previous prime is 309968629. The next prime is 309968669. The reversal of 309968640 is 46869903.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30076 + ... + 39044.

It is an arithmetic number, because the mean of its divisors is an integer number (7639450).

Almost surely, 2^309968640 is an apocalyptic number.

309968640 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 309968640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (550040400).

309968640 is an abundant number, since it is smaller than the sum of its proper divisors (790112160).

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

309968640 is an equidigital number, since it uses as much as digits as its factorization.

309968640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8999 (or 8979 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The square root of 309968640 is about 17605.9262749791. The cubic root of 309968640 is about 676.7671227931.

The spelling of 309968640 in words is "three hundred nine million, nine hundred sixty-eight thousand, six hundred forty".