646664787 has 6 divisors (see below), whose sum is σ = 934071372. Its totient is φ = 431109852.

The previous prime is 646664783. The next prime is 646664813. The reversal of 646664787 is 787466646.

It is a happy number.

It is not a de Polignac number, because 646664787 - 2² = 646664783 is a prime.

It is not an unprimeable number, because it can be changed into a prime (646664783) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35925813 + ... + 35925830.

It is an arithmetic number, because the mean of its divisors is an integer number (155678562).

Almost surely, 2^646664787 is an apocalyptic number.

646664787 is a deficient number, since it is larger than the sum of its proper divisors (287406585).

646664787 is a wasteful number, since it uses less digits than its factorization.

646664787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71851649 (or 71851646 counting only the distinct ones).

The product of its digits is 8128512, while the sum is 54.

The square root of 646664787 is about 25429.6045388048. The cubic root of 646664787 is about 864.7549784367.

It can be divided in two parts, 6466 and 64787, that added together give a triangular number (71253 = T₃₇₇).

The spelling of 646664787 in words is "six hundred forty-six million, six hundred sixty-four thousand, seven hundred eighty-seven".