90090991901 has 4 divisors (see below), whose sum is σ = 92525883612. Its totient is φ = 87656100192.

The previous prime is 90090991891. The next prime is 90090991931. The reversal of 90090991901 is 10919909009.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10919909009 = 181 ⋅60330989.

It can be written as a sum of positive squares in 2 ways, for example, as 32634422500 + 57456569401 = 180650^2 + 239701^2 .

It is a cyclic number.

It is not a de Polignac number, because 90090991901 - 2¹⁴ = 90090975517 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 (90090991931) 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, 1217445800 + ... + 1217445873.

It is an arithmetic number, because the mean of its divisors is an integer number (23131470903).

Almost surely, 2^90090991901 is an apocalyptic number.

It is an amenable number.

90090991901 is a deficient number, since it is larger than the sum of its proper divisors (2434891711).

90090991901 is a wasteful number, since it uses less digits than its factorization.

90090991901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2434891710.

The product of its (nonzero) digits is 59049, while the sum is 47.

The spelling of 90090991901 in words is "ninety billion, ninety million, nine hundred ninety-one thousand, nine hundred one".