639145723 has 2 divisors, whose sum is σ = 639145724. Its totient is φ = 639145722.

The previous prime is 639145691. The next prime is 639145729. The reversal of 639145723 is 327541936.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639145723 - 2⁵ = 639145691 is a prime.

It is not a weakly prime, because it can be changed into another prime (639145729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319572861 + 319572862.

It is an arithmetic number, because the mean of its divisors is an integer number (319572862).

Almost surely, 2^639145723 is an apocalyptic number.

639145723 is a deficient number, since it is larger than the sum of its proper divisors (1).

639145723 is an equidigital number, since it uses as much as digits as its factorization.

639145723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 40.

The square root of 639145723 is about 25281.3315116115. The cubic root of 639145723 is about 861.3902711151.

The spelling of 639145723 in words is "six hundred thirty-nine million, one hundred forty-five thousand, seven hundred twenty-three".