91023021 has 10 divisors (see below), whose sum is σ = 135972782. Its totient is φ = 60681960.

The previous prime is 91023019. The next prime is 91023047. The reversal of 91023021 is 12032019.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 79388100 + 11634921 = 8910^2 + 3411^2 .

It is not a de Polignac number, because 91023021 - 2¹ = 91023019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91022985 and 91023003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91023011) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 561790 + ... + 561951.

Almost surely, 2^91023021 is an apocalyptic number.

It is an amenable number.

91023021 is a deficient number, since it is larger than the sum of its proper divisors (44949761).

91023021 is a wasteful number, since it uses less digits than its factorization.

91023021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1123753 (or 1123744 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 91023021 is about 9540.5985661278. The cubic root of 91023021 is about 449.8320706739.

The spelling of 91023021 in words is "ninety-one million, twenty-three thousand, twenty-one".