640073723 has 2 divisors, whose sum is σ = 640073724. Its totient is φ = 640073722.

The previous prime is 640073719. The next prime is 640073741. The reversal of 640073723 is 327370046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640073723 - 2² = 640073719 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640073723.

It is not a weakly prime, because it can be changed into another prime (640073773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320036861 + 320036862.

It is an arithmetic number, because the mean of its divisors is an integer number (320036862).

Almost surely, 2^640073723 is an apocalyptic number.

640073723 is a deficient number, since it is larger than the sum of its proper divisors (1).

640073723 is an equidigital number, since it uses as much as digits as its factorization.

640073723 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21168, while the sum is 32.

The square root of 640073723 is about 25299.6783181131. The cubic root of 640073723 is about 861.8069646149.

The spelling of 640073723 in words is "six hundred forty million, seventy-three thousand, seven hundred twenty-three".