91661572039 has 4 divisors (see below), whose sum is σ = 91662243400. Its totient is φ = 91660900680.

The previous prime is 91661572031. The next prime is 91661572097. The reversal of 91661572039 is 93027516619.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 91661572039 - 2³ = 91661572031 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91661571983 and 91661572001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91661572031) 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, 49632 + ... + 431029.

It is an arithmetic number, because the mean of its divisors is an integer number (22915560850).

Almost surely, 2^91661572039 is an apocalyptic number.

91661572039 is a deficient number, since it is larger than the sum of its proper divisors (671361).

91661572039 is a wasteful number, since it uses less digits than its factorization.

91661572039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 671360.

The product of its (nonzero) digits is 612360, while the sum is 49.

The spelling of 91661572039 in words is "ninety-one billion, six hundred sixty-one million, five hundred seventy-two thousand, thirty-nine".