646720754 has 4 divisors (see below), whose sum is σ = 970081134. Its totient is φ = 323360376.

The previous prime is 646720741. The next prime is 646720801. The reversal of 646720754 is 457027646.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 450076225 + 196644529 = 21215^2 + 14023^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161680187 + ... + 161680190.

Almost surely, 2^646720754 is an apocalyptic number.

646720754 is a deficient number, since it is larger than the sum of its proper divisors (323360380).

646720754 is a wasteful number, since it uses less digits than its factorization.

646720754 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323360379.

The product of its (nonzero) digits is 282240, while the sum is 41.

The square root of 646720754 is about 25430.7049450069. The cubic root of 646720754 is about 864.7799250792.

The spelling of 646720754 in words is "six hundred forty-six million, seven hundred twenty thousand, seven hundred fifty-four".