991664026 has 32 divisors (see below), whose sum is σ = 1614495888. Its totient is φ = 455070720.

The previous prime is 991663993. The next prime is 991664033. The reversal of 991664026 is 620466199.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 731648401 + 260015625 = 27049^2 + 16125^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 310156 + ... + 313336.

Almost surely, 2^991664026 is an apocalyptic number.

991664026 is a deficient number, since it is larger than the sum of its proper divisors (622831862).

991664026 is a wasteful number, since it uses less digits than its factorization.

991664026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3426.

The product of its (nonzero) digits is 139968, while the sum is 43.

The square root of 991664026 is about 31490.6974517872. The cubic root of 991664026 is about 997.2135851034.

The spelling of 991664026 in words is "nine hundred ninety-one million, six hundred sixty-four thousand, twenty-six".