636999994 has 4 divisors (see below), whose sum is σ = 955499994. Its totient is φ = 318499996.

The previous prime is 636999991. The next prime is 637000009. The reversal of 636999994 is 499999636.

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., 465049225 + 171950769 = 21565^2 + 13113^2 .

It is not an unprimeable number, because it can be changed into a prime (636999991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159249997 + ... + 159250000.

Almost surely, 2^636999994 is an apocalyptic number.

636999994 is a deficient number, since it is larger than the sum of its proper divisors (318500000).

636999994 is a wasteful number, since it uses less digits than its factorization.

636999994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 318499999.

The product of its digits is 25509168, while the sum is 64.

The square root of 636999994 is about 25238.8588093836. The cubic root of 636999994 is about 860.4252421937.

The spelling of 636999994 in words is "six hundred thirty-six million, nine hundred ninety-nine thousand, nine hundred ninety-four".