640424737 has 2 divisors, whose sum is σ = 640424738. Its totient is φ = 640424736.

The previous prime is 640424699. The next prime is 640424747. The reversal of 640424737 is 737424046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 597509136 + 42915601 = 24444^2 + 6551^2 .

It is a cyclic number.

It is not a de Polignac number, because 640424737 - 2²³ = 632036129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640424696 and 640424705.

It is not a weakly prime, because it can be changed into another prime (640424747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320212368 + 320212369.

It is an arithmetic number, because the mean of its divisors is an integer number (320212369).

Almost surely, 2^640424737 is an apocalyptic number.

It is an amenable number.

640424737 is a deficient number, since it is larger than the sum of its proper divisors (1).

640424737 is an equidigital number, since it uses as much as digits as its factorization.

640424737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112896, while the sum is 37.

The square root of 640424737 is about 25306.6144910772. The cubic root of 640424737 is about 861.9644730487.

The spelling of 640424737 in words is "six hundred forty million, four hundred twenty-four thousand, seven hundred thirty-seven".