640662923 has 2 divisors, whose sum is σ = 640662924. Its totient is φ = 640662922.

The previous prime is 640662889. The next prime is 640662941. The reversal of 640662923 is 329266046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640662923 - 2⁸ = 640662667 is a prime.

It is not a weakly prime, because it can be changed into another prime (640664923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320331461 + 320331462.

It is an arithmetic number, because the mean of its divisors is an integer number (320331462).

Almost surely, 2^640662923 is an apocalyptic number.

640662923 is a deficient number, since it is larger than the sum of its proper divisors (1).

640662923 is an equidigital number, since it uses as much as digits as its factorization.

640662923 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 38.

The square root of 640662923 is about 25311.3200564491. The cubic root of 640662923 is about 862.0713200680.

The spelling of 640662923 in words is "six hundred forty million, six hundred sixty-two thousand, nine hundred twenty-three".