90990991901 has 4 divisors (see below), whose sum is σ = 90991616352. Its totient is φ = 90990367452.

The previous prime is 90990991877. The next prime is 90990991907. The reversal of 90990991901 is 10919909909.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 10919909909 = 11243 ⋅971263.

It is a cyclic number.

It is not a de Polignac number, because 90990991901 - 2¹⁸ = 90990729757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90990991907) 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, 35240 + ... + 428046.

It is an arithmetic number, because the mean of its divisors is an integer number (22747904088).

Almost surely, 2^90990991901 is an apocalyptic number.

It is an amenable number.

90990991901 is a deficient number, since it is larger than the sum of its proper divisors (624451).

90990991901 is a wasteful number, since it uses less digits than its factorization.

90990991901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624450.

The product of its (nonzero) digits is 531441, while the sum is 56.

The spelling of 90990991901 in words is "ninety billion, nine hundred ninety million, nine hundred ninety-one thousand, nine hundred one".