90987993 has 24 divisors (see below), whose sum is σ = 137521800. Its totient is φ = 57894144.

The previous prime is 90987973. The next prime is 90987997. The reversal of 90987993 is 39978909.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14197824 + 76790169 = 3768^2 + 8763^2 .

It is not a de Polignac number, because 90987993 - 2⁶ = 90987929 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (90987997) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21271 + ... + 25187.

It is an arithmetic number, because the mean of its divisors is an integer number (5730075).

Almost surely, 2^90987993 is an apocalyptic number.

It is an amenable number.

90987993 is a deficient number, since it is larger than the sum of its proper divisors (46533807).

90987993 is a wasteful number, since it uses less digits than its factorization.

90987993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4041 (or 4038 counting only the distinct ones).

The product of its (nonzero) digits is 1102248, while the sum is 54.

The square root of 90987993 is about 9538.7626556069. The cubic root of 90987993 is about 449.7743609530.

The spelling of 90987993 in words is "ninety million, nine hundred eighty-seven thousand, nine hundred ninety-three".