36661981 has 2 divisors, whose sum is σ = 36661982. Its totient is φ = 36661980.

The previous prime is 36661973. The next prime is 36661991. The reversal of 36661981 is 18916663.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28793956 + 7868025 = 5366^2 + 2805^2 .

It is a cyclic number.

It is not a de Polignac number, because 36661981 - 2³ = 36661973 is a prime.

It is a super-2 number, since 2×36661981² = 2688201701688722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (36661901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 18330990 + 18330991.

It is an arithmetic number, because the mean of its divisors is an integer number (18330991).

Almost surely, 2^36661981 is an apocalyptic number.

It is an amenable number.

36661981 is a deficient number, since it is larger than the sum of its proper divisors (1).

36661981 is an equidigital number, since it uses as much as digits as its factorization.

36661981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 40.

The square root of 36661981 is about 6054.9137896423. The cubic root of 36661981 is about 332.2043457001.

The spelling of 36661981 in words is "thirty-six million, six hundred sixty-one thousand, nine hundred eighty-one".