90990090 has 24 divisors (see below), whose sum is σ = 236574468. Its totient is φ = 24264000.

The previous prime is 90990077. The next prime is 90990091. The reversal of 90990090 is 9009909.

It can be written as a sum of positive squares in 2 ways, for example, as 90954369 + 35721 = 9537^2 + 189^2 .

It is not an unprimeable number, because it can be changed into a prime (90990091) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 505411 + ... + 505590.

Almost surely, 2^90990090 is an apocalyptic number.

90990090 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

90990090 is an abundant number, since it is smaller than the sum of its proper divisors (145584378).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

90990090 is a wasteful number, since it uses less digits than its factorization.

90990090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011014 (or 1011011 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 36.

The square root of 90990090 is about 9538.8725748906. The cubic root of 90990090 is about 449.7778162426. Note that the first 3 decimals are identical.

Adding to 90990090 its reverse (9009909), we get a palindrome (99999999).

The spelling of 90990090 in words is "ninety million, nine hundred ninety thousand, ninety".