89981981 has 2 divisors, whose sum is σ = 89981982. Its totient is φ = 89981980.

The previous prime is 89981963. The next prime is 89981993. The reversal of 89981981 is 18918998.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73376356 + 16605625 = 8566^2 + 4075^2 .

It is a cyclic number.

It is not a de Polignac number, because 89981981 - 2¹⁴ = 89965597 is a prime.

It is a super-2 number, since 2×89981981² = 16193513809368722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (89981081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 44990990 + 44990991.

It is an arithmetic number, because the mean of its divisors is an integer number (44990991).

Almost surely, 2^89981981 is an apocalyptic number.

It is an amenable number.

89981981 is a deficient number, since it is larger than the sum of its proper divisors (1).

89981981 is an equidigital number, since it uses as much as digits as its factorization.

89981981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 53.

The square root of 89981981 is about 9485.8832482800. The cubic root of 89981981 is about 448.1105650921.

The spelling of 89981981 in words is "eighty-nine million, nine hundred eighty-one thousand, nine hundred eighty-one".