645601256461 has 4 divisors (see below), whose sum is σ = 737830007392. Its totient is φ = 553372505532.

The previous prime is 645601256441. The next prime is 645601256479. The reversal of 645601256461 is 164652106546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 645601256461 - 2²³ = 645592867853 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 (645601256441) 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, 46114375455 + ... + 46114375468.

It is an arithmetic number, because the mean of its divisors is an integer number (184457501848).

Almost surely, 2^645601256461 is an apocalyptic number.

It is an amenable number.

645601256461 is a deficient number, since it is larger than the sum of its proper divisors (92228750931).

645601256461 is an equidigital number, since it uses as much as digits as its factorization.

645601256461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92228750930.

The product of its (nonzero) digits is 1036800, while the sum is 46.

The spelling of 645601256461 in words is "six hundred forty-five billion, six hundred one million, two hundred fifty-six thousand, four hundred sixty-one".