645412751 has 4 divisors (see below), whose sum is σ = 645469104. Its totient is φ = 645356400.

The previous prime is 645412739. The next prime is 645412753. The reversal of 645412751 is 157214546.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 157214546 = 2 ⋅78607273.

It is a cyclic number.

It is not a de Polignac number, because 645412751 - 2¹⁰ = 645411727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645412753) 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, 4190 + ... + 36171.

It is an arithmetic number, because the mean of its divisors is an integer number (161367276).

Almost surely, 2^645412751 is an apocalyptic number.

645412751 is a deficient number, since it is larger than the sum of its proper divisors (56353).

645412751 is a wasteful number, since it uses less digits than its factorization.

645412751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56352.

The product of its digits is 33600, while the sum is 35.

The square root of 645412751 is about 25404.9749261833. The cubic root of 645412751 is about 864.1965212084.

The spelling of 645412751 in words is "six hundred forty-five million, four hundred twelve thousand, seven hundred fifty-one".