645992816 has 40 divisors (see below), whose sum is σ = 1460858880. Its totient is φ = 270961344.

The previous prime is 645992813. The next prime is 645992819. The reversal of 645992816 is 618299546.

It is an interprime number because it is at equal distance from previous prime (645992813) and next prime (645992819).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645992813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56096 + ... + 66623.

It is an arithmetic number, because the mean of its divisors is an integer number (36521472).

Almost surely, 2^645992816 is an apocalyptic number.

It is an amenable number.

645992816 is an abundant number, since it is smaller than the sum of its proper divisors (814866064).

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

645992816 is a wasteful number, since it uses less digits than its factorization.

645992816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122781 (or 122775 counting only the distinct ones).

The product of its digits is 933120, while the sum is 50.

The square root of 645992816 is about 25416.3887285350. The cubic root of 645992816 is about 864.4553426891.

The spelling of 645992816 in words is "six hundred forty-five million, nine hundred ninety-two thousand, eight hundred sixteen".