645220443870 has 96 divisors (see below), whose sum is σ = 1773646692480. Its totient is φ = 162284886720.

The previous prime is 645220443859. The next prime is 645220443911. The reversal of 645220443870 is 78344022546.

It is a happy number.

645220443870 is a `hidden beast` number, since 6 + 4 + 5 + 2 + 204 + 438 + 7 + 0 = 666.

645220443870 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 47 ways as a sum of consecutive naturals, for example, 442936 + ... + 1219275.

It is an arithmetic number, because the mean of its divisors is an integer number (18475486380).

Almost surely, 2^645220443870 is an apocalyptic number.

645220443870 is an abundant number, since it is smaller than the sum of its proper divisors (1128426248610).

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

645220443870 is a wasteful number, since it uses less digits than its factorization.

645220443870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1662470 (or 1662467 counting only the distinct ones).

The product of its (nonzero) digits is 1290240, while the sum is 45.

The spelling of 645220443870 in words is "six hundred forty-five billion, two hundred twenty million, four hundred forty-three thousand, eight hundred seventy".