1620865720 has 32 divisors (see below), whose sum is σ = 3696912720. Its totient is φ = 639463680.

The previous prime is 1620865717. The next prime is 1620865733. The reversal of 1620865720 is 275680261.

It is a happy number.

It is a super-2 number, since 2×1620865720² = 5254411364542236800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1620865720.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 274626 + ... + 280465.

Almost surely, 2^1620865720 is an apocalyptic number.

1620865720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1620865720 is an abundant number, since it is smaller than the sum of its proper divisors (2076047000).

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

1620865720 is a wasteful number, since it uses less digits than its factorization.

1620865720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555175 (or 555171 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 1620865720 is about 40259.9766517568. The cubic root of 1620865720 is about 1174.6694636885.

The spelling of 1620865720 in words is "one billion, six hundred twenty million, eight hundred sixty-five thousand, seven hundred twenty".