645291901 has 2 divisors, whose sum is σ = 645291902. Its totient is φ = 645291900.

The previous prime is 645291863. The next prime is 645291923. The reversal of 645291901 is 109192546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 643839876 + 1452025 = 25374^2 + 1205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645291901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645291971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322645950 + 322645951.

It is an arithmetic number, because the mean of its divisors is an integer number (322645951).

Almost surely, 2^645291901 is an apocalyptic number.

It is an amenable number.

645291901 is a deficient number, since it is larger than the sum of its proper divisors (1).

645291901 is an equidigital number, since it uses as much as digits as its factorization.

645291901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 645291901 is about 25402.5963436811. The cubic root of 645291901 is about 864.1425791542.

It can be divided in two parts, 64529 and 1901, that added together give a triangular number (66430 = T₃₆₄).

The spelling of 645291901 in words is "six hundred forty-five million, two hundred ninety-one thousand, nine hundred one".