91251710621 has 4 divisors (see below), whose sum is σ = 91254402492. Its totient is φ = 91249018752.

The previous prime is 91251710597. The next prime is 91251710633. The reversal of 91251710621 is 12601715219.

It is a happy number.

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 71401718521 + 19849992100 = 267211^2 + 140890^2 .

It is a cyclic number.

It is not a de Polignac number, because 91251710621 - 2¹⁰ = 91251709597 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 (91251700621) 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, 1294430 + ... + 1363103.

It is an arithmetic number, because the mean of its divisors is an integer number (22813600623).

Almost surely, 2^91251710621 is an apocalyptic number.

It is an amenable number.

91251710621 is a deficient number, since it is larger than the sum of its proper divisors (2691871).

91251710621 is a wasteful number, since it uses less digits than its factorization.

91251710621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2691870.

The product of its (nonzero) digits is 7560, while the sum is 35.

The spelling of 91251710621 in words is "ninety-one billion, two hundred fifty-one million, seven hundred ten thousand, six hundred twenty-one".