647123691 has 4 divisors (see below), whose sum is σ = 862831592. Its totient is φ = 431415792.

The previous prime is 647123651. The next prime is 647123723. The reversal of 647123691 is 196321746.

647123691 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 647123691 - 2¹³ = 647115499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647123621) 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, 107853946 + ... + 107853951.

It is an arithmetic number, because the mean of its divisors is an integer number (215707898).

Almost surely, 2^647123691 is an apocalyptic number.

647123691 is a deficient number, since it is larger than the sum of its proper divisors (215707901).

647123691 is a wasteful number, since it uses less digits than its factorization.

647123691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215707900.

The product of its digits is 54432, while the sum is 39.

The square root of 647123691 is about 25438.6259652521. The cubic root of 647123691 is about 864.9594871155.

The spelling of 647123691 in words is "six hundred forty-seven million, one hundred twenty-three thousand, six hundred ninety-one".