91020561 has 16 divisors (see below), whose sum is σ = 124604160. Its totient is φ = 59080320.

The previous prime is 91020541. The next prime is 91020563. The reversal of 91020561 is 16502019.

It is not a de Polignac number, because 91020561 - 2⁹ = 91020049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91020563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14671 + ... + 19931.

It is an arithmetic number, because the mean of its divisors is an integer number (7787760).

Almost surely, 2^91020561 is an apocalyptic number.

It is an amenable number.

91020561 is a deficient number, since it is larger than the sum of its proper divisors (33583599).

91020561 is a wasteful number, since it uses less digits than its factorization.

91020561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5416.

The product of its (nonzero) digits is 540, while the sum is 24.

The square root of 91020561 is about 9540.4696425281. The cubic root of 91020561 is about 449.8280182307.

The spelling of 91020561 in words is "ninety-one million, twenty thousand, five hundred sixty-one".