90720891 has 24 divisors (see below), whose sum is σ = 143895024. Its totient is φ = 56920320.

The previous prime is 90720871. The next prime is 90720919. The reversal of 90720891 is 19802709.

It is a happy number.

It is not a de Polignac number, because 90720891 - 2¹¹ = 90718843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (90720871) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6850 + ... + 15111.

It is an arithmetic number, because the mean of its divisors is an integer number (5995626).

Almost surely, 2^90720891 is an apocalyptic number.

90720891 is a deficient number, since it is larger than the sum of its proper divisors (53174133).

90720891 is a wasteful number, since it uses less digits than its factorization.

90720891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21993 (or 21981 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 90720891 is about 9524.7514928212. The cubic root of 90720891 is about 449.3338142568. Note that the first 3 decimals are identical.

The spelling of 90720891 in words is "ninety million, seven hundred twenty thousand, eight hundred ninety-one".