645387998 has 4 divisors (see below), whose sum is σ = 968082000. Its totient is φ = 322693998.

The previous prime is 645387971. The next prime is 645388031. The reversal of 645387998 is 899783546.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161346998 + ... + 161347001.

It is an arithmetic number, because the mean of its divisors is an integer number (242020500).

Almost surely, 2^645387998 is an apocalyptic number.

645387998 is a deficient number, since it is larger than the sum of its proper divisors (322694002).

645387998 is a wasteful number, since it uses less digits than its factorization.

645387998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322694001.

The product of its digits is 13063680, while the sum is 59.

The square root of 645387998 is about 25404.4877531510. The cubic root of 645387998 is about 864.1854731207.

The spelling of 645387998 in words is "six hundred forty-five million, three hundred eighty-seven thousand, nine hundred ninety-eight".