90611981 has 2 divisors, whose sum is σ = 90611982. Its totient is φ = 90611980.

The previous prime is 90611953. The next prime is 90612043. The reversal of 90611981 is 18911609.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90079081 + 532900 = 9491^2 + 730^2 .

It is a cyclic number.

It is not a de Polignac number, because 90611981 - 2¹⁰ = 90610957 is a prime.

It is a super-2 number, since 2×90611981² = 16421062201488722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90611281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45305990 + 45305991.

It is an arithmetic number, because the mean of its divisors is an integer number (45305991).

Almost surely, 2^90611981 is an apocalyptic number.

It is an amenable number.

90611981 is a deficient number, since it is larger than the sum of its proper divisors (1).

90611981 is an equidigital number, since it uses as much as digits as its factorization.

90611981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 35.

The square root of 90611981 is about 9519.0325663903. The cubic root of 90611981 is about 449.1539345507.

The spelling of 90611981 in words is "ninety million, six hundred eleven thousand, nine hundred eighty-one".