90161820 has 144 divisors (see below), whose sum is σ = 315194880. Its totient is φ = 20435328.

The previous prime is 90161809. The next prime is 90161849. The reversal of 90161820 is 2816109.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 205161 + ... + 205599.

Almost surely, 2^90161820 is an apocalyptic number.

90161820 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 90161820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157597440).

90161820 is an abundant number, since it is smaller than the sum of its proper divisors (225033060).

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

90161820 is a wasteful number, since it uses less digits than its factorization.

90161820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624 (or 619 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 90161820 is about 9495.3578131632. The cubic root of 90161820 is about 448.4088993685.

Adding to 90161820 its reverse (2816109), we get a palindrome (92977929).

The spelling of 90161820 in words is "ninety million, one hundred sixty-one thousand, eight hundred twenty".