649780091 has 4 divisors (see below), whose sum is σ = 649924800. Its totient is φ = 649635384.

The previous prime is 649780073. The next prime is 649780093. The reversal of 649780091 is 190087946.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-649780091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649780093) 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, 65396 + ... + 74673.

It is an arithmetic number, because the mean of its divisors is an integer number (162481200).

Almost surely, 2^649780091 is an apocalyptic number.

649780091 is a deficient number, since it is larger than the sum of its proper divisors (144709).

649780091 is a wasteful number, since it uses less digits than its factorization.

649780091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144708.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 649780091 is about 25490.7844328102. The cubic root of 649780091 is about 866.1414052065.

The spelling of 649780091 in words is "six hundred forty-nine million, seven hundred eighty thousand, ninety-one".