991660416 has 48 divisors (see below), whose sum is σ = 2635738140. Its totient is φ = 330347776.

The previous prime is 991660409. The next prime is 991660429. The reversal of 991660416 is 614066199.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×991660416² = 1966780761322586112, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 616285 + ... + 617891.

Almost surely, 2^991660416 is an apocalyptic number.

991660416 is a gapful number since it is divisible by the number (96) formed by its first and last digit.

It is an amenable number.

991660416 is an abundant number, since it is smaller than the sum of its proper divisors (1644077724).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991660416 is an frugal number, since it uses more digits than its factorization.

991660416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3231 (or 1612 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 42.

The square root of 991660416 is about 31490.6401332205. The cubic root of 991660416 is about 997.2123750345.

Multiplying 991660416 by its product of nonzero digits (69984), we get a square (69400362553344 = 8330688²).

The spelling of 991660416 in words is "nine hundred ninety-one million, six hundred sixty thousand, four hundred sixteen".