645739240 has 32 divisors (see below), whose sum is σ = 1457131680. Its totient is φ = 257545792.

The previous prime is 645739231. The next prime is 645739261. The reversal of 645739240 is 42937546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 645739193 and 645739202.

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, 9382 + ... + 37141.

It is an arithmetic number, because the mean of its divisors is an integer number (45535365).

Almost surely, 2^645739240 is an apocalyptic number.

It is an amenable number.

645739240 is an abundant number, since it is smaller than the sum of its proper divisors (811392440).

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

645739240 is a wasteful number, since it uses less digits than its factorization.

645739240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46881 (or 46877 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 40.

The square root of 645739240 is about 25411.3998040250. The cubic root of 645739240 is about 864.3422176869.

The spelling of 645739240 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, two hundred forty".