991963509 has 8 divisors (see below), whose sum is σ = 1334979360. Its totient is φ = 655128336.

The previous prime is 991963499. The next prime is 991963537. The reversal of 991963509 is 905369199.

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

It is not a de Polignac number, because 991963509 - 2⁸ = 991963253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991913509) 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, 1544794 + ... + 1545435.

It is an arithmetic number, because the mean of its divisors is an integer number (166872420).

Almost surely, 2^991963509 is an apocalyptic number.

It is an amenable number.

991963509 is a deficient number, since it is larger than the sum of its proper divisors (343015851).

991963509 is a wasteful number, since it uses less digits than its factorization.

991963509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3090339.

The product of its (nonzero) digits is 590490, while the sum is 51.

The square root of 991963509 is about 31495.4521955155. The cubic root of 991963509 is about 997.3139613226.

The spelling of 991963509 in words is "nine hundred ninety-one million, nine hundred sixty-three thousand, five hundred nine".