90999891 has 12 divisors (see below), whose sum is σ = 137159568. Its totient is φ = 58028784.

The previous prime is 90999859. The next prime is 90999899. The reversal of 90999891 is 19899909.

It is not a de Polignac number, because 90999891 - 2⁵ = 90999859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (90999899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 219600 + ... + 220013.

It is an arithmetic number, because the mean of its divisors is an integer number (11429964).

Almost surely, 2^90999891 is an apocalyptic number.

90999891 is a deficient number, since it is larger than the sum of its proper divisors (46159677).

90999891 is a wasteful number, since it uses less digits than its factorization.

90999891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439642 (or 439639 counting only the distinct ones).

The product of its (nonzero) digits is 472392, while the sum is 54.

The square root of 90999891 is about 9539.3863010154. The cubic root of 90999891 is about 449.7939649393.

The spelling of 90999891 in words is "ninety million, nine hundred ninety-nine thousand, eight hundred ninety-one".