81989701 has 2 divisors, whose sum is σ = 81989702. Its totient is φ = 81989700.

The previous prime is 81989659. The next prime is 81989707. The reversal of 81989701 is 10798918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48650625 + 33339076 = 6975^2 + 5774^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81989701 is a prime.

It is a super-2 number, since 2×81989701² = 13444622140138802, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81989707) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40994850 + 40994851.

It is an arithmetic number, because the mean of its divisors is an integer number (40994851).

Almost surely, 2^81989701 is an apocalyptic number.

It is an amenable number.

81989701 is a deficient number, since it is larger than the sum of its proper divisors (1).

81989701 is an equidigital number, since it uses as much as digits as its factorization.

81989701 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 81989701 is about 9054.8164531370. The cubic root of 81989701 is about 434.4299592727.

The spelling of 81989701 in words is "eighty-one million, nine hundred eighty-nine thousand, seven hundred one".