645180691 has 4 divisors (see below), whose sum is σ = 647751384. Its totient is φ = 642610000.

The previous prime is 645180671. The next prime is 645180737. The reversal of 645180691 is 196081546.

645180691 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 645180691 - 2⁷ = 645180563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645180611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1284970 + ... + 1285471.

It is an arithmetic number, because the mean of its divisors is an integer number (161937846).

Almost surely, 2^645180691 is an apocalyptic number.

645180691 is a deficient number, since it is larger than the sum of its proper divisors (2570693).

645180691 is a wasteful number, since it uses less digits than its factorization.

645180691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2570692.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 645180691 is about 25400.4072998840. The cubic root of 645180691 is about 864.0929340156.

The spelling of 645180691 in words is "six hundred forty-five million, one hundred eighty thousand, six hundred ninety-one".