645212556 has 18 divisors (see below), whose sum is σ = 1630954052. Its totient is φ = 215070840.

The previous prime is 645212539. The next prime is 645212573. The reversal of 645212556 is 655212546.

645212556 is a `hidden beast` number, since 64 + 521 + 25 + 56 = 666.

It is an interprime number because it is at equal distance from previous prime (645212539) and next prime (645212573).

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 17922571 = 645212556 / (6 + 4 + 5 + 2 + 1 + 2 + 5 + 5 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 645212556.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8961250 + ... + 8961321.

Almost surely, 2^645212556 is an apocalyptic number.

It is an amenable number.

645212556 is an abundant number, since it is smaller than the sum of its proper divisors (985741496).

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

645212556 is a wasteful number, since it uses less digits than its factorization.

645212556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17922581 (or 17922576 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 645212556 is about 25401.0345458605. The cubic root of 645212556 is about 864.1071594197.

The spelling of 645212556 in words is "six hundred forty-five million, two hundred twelve thousand, five hundred fifty-six".