645871620 has 48 divisors (see below), whose sum is σ = 1814662080. Its totient is φ = 171639936.

The previous prime is 645871609. The next prime is 645871631. The reversal of 645871620 is 26178546.

It is an interprime number because it is at equal distance from previous prime (645871609) and next prime (645871631).

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, 790 + ... + 35949.

It is an arithmetic number, because the mean of its divisors is an integer number (37805460).

Almost surely, 2^645871620 is an apocalyptic number.

645871620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645871620 is an abundant number, since it is smaller than the sum of its proper divisors (1168790460).

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

645871620 is a wasteful number, since it uses less digits than its factorization.

645871620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37044 (or 37042 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 645871620 is about 25414.0044070194. The cubic root of 645871620 is about 864.4012785779.

The spelling of 645871620 in words is "six hundred forty-five million, eight hundred seventy-one thousand, six hundred twenty".