642657956 has 6 divisors (see below), whose sum is σ = 1124651430. Its totient is φ = 321328976.

The previous prime is 642657949. The next prime is 642657971. The reversal of 642657956 is 659756246.

It can be written as a sum of positive squares in only one way, i.e., 641811556 + 846400 = 25334^2 + 920^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80332241 + ... + 80332248.

It is an arithmetic number, because the mean of its divisors is an integer number (187441905).

Almost surely, 2^642657956 is an apocalyptic number.

It is an amenable number.

642657956 is a deficient number, since it is larger than the sum of its proper divisors (481993474).

642657956 is a wasteful number, since it uses less digits than its factorization.

642657956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160664493 (or 160664491 counting only the distinct ones).

The product of its digits is 2721600, while the sum is 50.

The square root of 642657956 is about 25350.6993197426. The cubic root of 642657956 is about 862.9652267434.

The spelling of 642657956 in words is "six hundred forty-two million, six hundred fifty-seven thousand, nine hundred fifty-six".