645902751 has 16 divisors (see below), whose sum is σ = 929997824. Its totient is φ = 396386784.

The previous prime is 645902729. The next prime is 645902753. The reversal of 645902751 is 157209546.

It is not a de Polignac number, because 645902751 - 2¹⁸ = 645640607 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645902753) 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, 8251 + ... + 36876.

It is an arithmetic number, because the mean of its divisors is an integer number (58124864).

Almost surely, 2^645902751 is an apocalyptic number.

645902751 is a deficient number, since it is larger than the sum of its proper divisors (284095073).

645902751 is a wasteful number, since it uses less digits than its factorization.

645902751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45510.

The product of its (nonzero) digits is 75600, while the sum is 39.

The square root of 645902751 is about 25414.6168769077. The cubic root of 645902751 is about 864.4151663966.

The spelling of 645902751 in words is "six hundred forty-five million, nine hundred two thousand, seven hundred fifty-one".