645739251 has 8 divisors (see below), whose sum is σ = 879304704. Its totient is φ = 421333320.

The previous prime is 645739231. The next prime is 645739261. The reversal of 645739251 is 152937546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 645739251 - 2⁵ = 645739219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645739231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2289715 + ... + 2289996.

It is an arithmetic number, because the mean of its divisors is an integer number (109913088).

Almost surely, 2^645739251 is an apocalyptic number.

645739251 is a deficient number, since it is larger than the sum of its proper divisors (233565453).

645739251 is a wasteful number, since it uses less digits than its factorization.

645739251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4579761.

The product of its digits is 226800, while the sum is 42.

The square root of 645739251 is about 25411.4000204633. The cubic root of 645739251 is about 864.3422225948.

The spelling of 645739251 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, two hundred fifty-one".