991916402501 has 4 divisors (see below), whose sum is σ = 992111782092. Its totient is φ = 991721022912.

The previous prime is 991916402473. The next prime is 991916402567. The reversal of 991916402501 is 105204619199.

It is a Cunningham number, because it is equal to 995950²+1.

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

It can be written as a sum of positive squares in 2 ways, for example, as 963982294276 + 27934108225 = 981826^2 + 167135^2 .

It is a cyclic number.

It is not a de Polignac number, because 991916402501 - 2¹⁰ = 991916401477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991916402401) 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, 97682180 + ... + 97692333.

It is an arithmetic number, because the mean of its divisors is an integer number (248027945523).

Almost surely, 2^991916402501 is an apocalyptic number.

It is an amenable number.

991916402501 is a deficient number, since it is larger than the sum of its proper divisors (195379591).

991916402501 is a wasteful number, since it uses less digits than its factorization.

991916402501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195379590.

The product of its (nonzero) digits is 174960, while the sum is 47.

The spelling of 991916402501 in words is "nine hundred ninety-one billion, nine hundred sixteen million, four hundred two thousand, five hundred one".