91021816 has 16 divisors (see below), whose sum is σ = 171226440. Its totient is φ = 45361440.

The previous prime is 91021771. The next prime is 91021817. The reversal of 91021816 is 61812019.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91021817) 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, 16075 + ... + 20986.

Almost surely, 2^91021816 is an apocalyptic number.

It is an amenable number.

91021816 is a deficient number, since it is larger than the sum of its proper divisors (80204624).

91021816 is a wasteful number, since it uses less digits than its factorization.

91021816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37374 (or 37370 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 91021816 is about 9540.5354147448. The cubic root of 91021816 is about 449.8300856448.

The spelling of 91021816 in words is "ninety-one million, twenty-one thousand, eight hundred sixteen".