6649138693 has 4 divisors (see below), whose sum is σ = 6649400160. Its totient is φ = 6648877228.

The previous prime is 6649138679. The next prime is 6649138723. The reversal of 6649138693 is 3968319466.

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 6649138693 - 2¹⁷ = 6649007621 is a prime.

It is a super-2 number, since 2×6649138693² = 88422090717499496498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6649138663) 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, 87913 + ... + 145006.

It is an arithmetic number, because the mean of its divisors is an integer number (1662350040).

Almost surely, 2^6649138693 is an apocalyptic number.

It is an amenable number.

6649138693 is a deficient number, since it is larger than the sum of its proper divisors (261467).

6649138693 is a wasteful number, since it uses less digits than its factorization.

6649138693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261466.

The product of its digits is 5038848, while the sum is 55.

The square root of 6649138693 is about 81542.2509684397. The cubic root of 6649138693 is about 1880.4211646017.

The spelling of 6649138693 in words is "six billion, six hundred forty-nine million, one hundred thirty-eight thousand, six hundred ninety-three".