647994561 has 4 divisors (see below), whose sum is σ = 863992752. Its totient is φ = 431996372.

The previous prime is 647994541. The next prime is 647994631. The reversal of 647994561 is 165499746.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 647994561 - 2⁶ = 647994497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (647994541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107999091 + ... + 107999096.

It is an arithmetic number, because the mean of its divisors is an integer number (215998188).

Almost surely, 2^647994561 is an apocalyptic number.

It is an amenable number.

647994561 is a deficient number, since it is larger than the sum of its proper divisors (215998191).

647994561 is a wasteful number, since it uses less digits than its factorization.

647994561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215998190.

The product of its digits is 1632960, while the sum is 51.

The square root of 647994561 is about 25455.7372904420. The cubic root of 647994561 is about 865.3473210680.

The spelling of 647994561 in words is "six hundred forty-seven million, nine hundred ninety-four thousand, five hundred sixty-one".