645387391 has 16 divisors (see below), whose sum is σ = 715852800. Its totient is φ = 576969120.

The previous prime is 645387377. The next prime is 645387397. The reversal of 645387391 is 193783546.

It is a cyclic number.

It is not a de Polignac number, because 645387391 - 2⁹ = 645386879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645387397) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 166906 + ... + 170728.

It is an arithmetic number, because the mean of its divisors is an integer number (44740800).

Almost surely, 2^645387391 is an apocalyptic number.

645387391 is a deficient number, since it is larger than the sum of its proper divisors (70465409).

645387391 is a wasteful number, since it uses less digits than its factorization.

645387391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4086.

The product of its digits is 544320, while the sum is 46.

The square root of 645387391 is about 25404.4758064401. The cubic root of 645387391 is about 864.1852021928.

The spelling of 645387391 in words is "six hundred forty-five million, three hundred eighty-seven thousand, three hundred ninety-one".