991564705 has 16 divisors (see below), whose sum is σ = 1220045904. Its totient is φ = 773176320.

The previous prime is 991564681. The next prime is 991564709. The reversal of 991564705 is 507465199.

It can be written as a sum of positive squares in 8 ways, for example, as 100721296 + 890843409 = 10036^2 + 29847^2 .

It is not a de Polignac number, because 991564705 - 2¹¹ = 991562657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991564709) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 345637 + ... + 348493.

It is an arithmetic number, because the mean of its divisors is an integer number (76252869).

Almost surely, 2^991564705 is an apocalyptic number.

It is an amenable number.

991564705 is a deficient number, since it is larger than the sum of its proper divisors (228481199).

991564705 is a wasteful number, since it uses less digits than its factorization.

991564705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4596.

The product of its (nonzero) digits is 340200, while the sum is 46.

The square root of 991564705 is about 31489.1204227746. The cubic root of 991564705 is about 997.1802917181.

The spelling of 991564705 in words is "nine hundred ninety-one million, five hundred sixty-four thousand, seven hundred five".