646780091 has 8 divisors (see below), whose sum is σ = 664854384. Its totient is φ = 628737120.

The previous prime is 646780081. The next prime is 646780097. The reversal of 646780091 is 190087646.

646780091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 646780091 - 2²² = 642585787 is a prime.

It is a super-2 number, since 2×646780091² = 836648972227936562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646780097) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37676 + ... + 52086.

It is an arithmetic number, because the mean of its divisors is an integer number (83106798).

Almost surely, 2^646780091 is an apocalyptic number.

646780091 is a deficient number, since it is larger than the sum of its proper divisors (18074293).

646780091 is a wasteful number, since it uses less digits than its factorization.

646780091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15661.

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 646780091 is about 25431.8715591283. The cubic root of 646780091 is about 864.8063722883.

The spelling of 646780091 in words is "six hundred forty-six million, seven hundred eighty thousand, ninety-one".