91199021 has 4 divisors (see below), whose sum is σ = 91597500. Its totient is φ = 90800544.

The previous prime is 91198967. The next prime is 91199039. The reversal of 91199021 is 12099119.

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 63520900 + 27678121 = 7970^2 + 5261^2 .

It is a cyclic number.

It is not a de Polignac number, because 91199021 - 2⁶ = 91198957 is a prime.

It is a super-2 number, since 2×91199021² = 16634522862716882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91199051) 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, 198896 + ... + 199353.

It is an arithmetic number, because the mean of its divisors is an integer number (22899375).

Almost surely, 2^91199021 is an apocalyptic number.

It is an amenable number.

91199021 is a deficient number, since it is larger than the sum of its proper divisors (398479).

91199021 is a wasteful number, since it uses less digits than its factorization.

91199021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398478.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 91199021 is about 9549.8178516661. The cubic root of 91199021 is about 450.1218122907.

The spelling of 91199021 in words is "ninety-one million, one hundred ninety-nine thousand, twenty-one".