647911994 has 4 divisors (see below), whose sum is σ = 971867994. Its totient is φ = 323955996.

The previous prime is 647911993. The next prime is 647912017. The reversal of 647911994 is 499119746.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 499119746 = 2 ⋅249559873.

It can be written as a sum of positive squares in only one way, i.e., 628153969 + 19758025 = 25063^2 + 4445^2 .

It is not an unprimeable number, because it can be changed into a prime (647911993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161977997 + ... + 161978000.

Almost surely, 2^647911994 is an apocalyptic number.

647911994 is a deficient number, since it is larger than the sum of its proper divisors (323956000).

647911994 is a wasteful number, since it uses less digits than its factorization.

647911994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323955999.

The product of its digits is 489888, while the sum is 50.

The square root of 647911994 is about 25454.1154629266. The cubic root of 647911994 is about 865.3105655295.

The spelling of 647911994 in words is "six hundred forty-seven million, nine hundred eleven thousand, nine hundred ninety-four".