645122651 has 4 divisors (see below), whose sum is σ = 645557400. Its totient is φ = 644687904.

The previous prime is 645122633. The next prime is 645122689. The reversal of 645122651 is 156221546.

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 645122651 - 2²² = 640928347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645122251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 215141 + ... + 218118.

It is an arithmetic number, because the mean of its divisors is an integer number (161389350).

Almost surely, 2^645122651 is an apocalyptic number.

645122651 is a deficient number, since it is larger than the sum of its proper divisors (434749).

645122651 is a wasteful number, since it uses less digits than its factorization.

645122651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434748.

The product of its digits is 14400, while the sum is 32.

The square root of 645122651 is about 25399.2647728236. The cubic root of 645122651 is about 864.0670221749.

The spelling of 645122651 in words is "six hundred forty-five million, one hundred twenty-two thousand, six hundred fifty-one".