90421981 has 4 divisors (see below), whose sum is σ = 97377532. Its totient is φ = 83466432.

The previous prime is 90421973. The next prime is 90421987. The reversal of 90421981 is 18912409.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13579225 + 76842756 = 3685^2 + 8766^2 .

It is a cyclic number.

It is not a de Polignac number, because 90421981 - 2³ = 90421973 is a prime.

It is a super-2 number, since 2×90421981² = 16352269295928722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90421987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3477756 + ... + 3477781.

It is an arithmetic number, because the mean of its divisors is an integer number (24344383).

Almost surely, 2^90421981 is an apocalyptic number.

It is an amenable number.

90421981 is a deficient number, since it is larger than the sum of its proper divisors (6955551).

90421981 is a wasteful number, since it uses less digits than its factorization.

90421981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6955550.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 90421981 is about 9509.0473234704. The cubic root of 90421981 is about 448.8397782836.

The spelling of 90421981 in words is "ninety million, four hundred twenty-one thousand, nine hundred eighty-one".