640450651 has 8 divisors (see below), whose sum is σ = 685211600. Its totient is φ = 596795040.

The previous prime is 640450637. The next prime is 640450661. The reversal of 640450651 is 156054046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640450651 - 2⁵ = 640450619 is a prime.

It is a super-3 number, since 3×640450651³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640450631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 275136 + ... + 277453.

It is an arithmetic number, because the mean of its divisors is an integer number (85651450).

Almost surely, 2^640450651 is an apocalyptic number.

640450651 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

640450651 is a deficient number, since it is larger than the sum of its proper divisors (44760949).

640450651 is a wasteful number, since it uses less digits than its factorization.

640450651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552669.

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 640450651 is about 25307.1264864267. The cubic root of 640450651 is about 861.9760990030.

The spelling of 640450651 in words is "six hundred forty million, four hundred fifty thousand, six hundred fifty-one".