640632457 has 2 divisors, whose sum is σ = 640632458. Its totient is φ = 640632456.

The previous prime is 640632407. The next prime is 640632463. The reversal of 640632457 is 754236046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 624800016 + 15832441 = 24996^2 + 3979^2 .

It is a cyclic number.

It is not a de Polignac number, because 640632457 - 2¹⁵ = 640599689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640632407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320316228 + 320316229.

It is an arithmetic number, because the mean of its divisors is an integer number (320316229).

Almost surely, 2^640632457 is an apocalyptic number.

It is an amenable number.

640632457 is a deficient number, since it is larger than the sum of its proper divisors (1).

640632457 is an equidigital number, since it uses as much as digits as its factorization.

640632457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 37.

The square root of 640632457 is about 25310.7182237091. The cubic root of 640632457 is about 862.0576549095.

The spelling of 640632457 in words is "six hundred forty million, six hundred thirty-two thousand, four hundred fifty-seven".