640021081451 has 4 divisors (see below), whose sum is σ = 640078653600. Its totient is φ = 639963509304.

The previous prime is 640021081417. The next prime is 640021081457. The reversal of 640021081451 is 154180120046.

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 640021081451 - 2³⁴ = 622841212267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640021081457) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 28769396 + ... + 28791633.

It is an arithmetic number, because the mean of its divisors is an integer number (160019663400).

Almost surely, 2^640021081451 is an apocalyptic number.

640021081451 is a deficient number, since it is larger than the sum of its proper divisors (57572149).

640021081451 is a wasteful number, since it uses less digits than its factorization.

640021081451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57572148.

The product of its (nonzero) digits is 7680, while the sum is 32.

The spelling of 640021081451 in words is "six hundred forty billion, twenty-one million, eighty-one thousand, four hundred fifty-one".