6440642645 has 16 divisors (see below), whose sum is σ = 7938943488. Its totient is φ = 5013087360.

The previous prime is 6440642623. The next prime is 6440642669. The reversal of 6440642645 is 5462460446.

It is not a de Polignac number, because 6440642645 - 2¹⁰ = 6440641621 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32432 + ... + 118038.

It is an arithmetic number, because the mean of its divisors is an integer number (496183968).

Almost surely, 2^6440642645 is an apocalyptic number.

It is an amenable number.

6440642645 is a deficient number, since it is larger than the sum of its proper divisors (1498300843).

6440642645 is a wasteful number, since it uses less digits than its factorization.

6440642645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86020.

The product of its (nonzero) digits is 552960, while the sum is 41.

The square root of 6440642645 is about 80253.6145291911. The cubic root of 6440642645 is about 1860.5573776630.

The spelling of 6440642645 in words is "six billion, four hundred forty million, six hundred forty-two thousand, six hundred forty-five".