36815981 has 2 divisors, whose sum is σ = 36815982. Its totient is φ = 36815980.

The previous prime is 36815971. The next prime is 36815983. The reversal of 36815981 is 18951863.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25593481 + 11222500 = 5059^2 + 3350^2 .

It is a cyclic number.

It is not a de Polignac number, because 36815981 - 2¹⁴ = 36799597 is a prime.

It is a super-2 number, since 2×36815981² = 2710832913984722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 36815983, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (36815983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 18407990 + 18407991.

It is an arithmetic number, because the mean of its divisors is an integer number (18407991).

Almost surely, 2^36815981 is an apocalyptic number.

It is an amenable number.

36815981 is a deficient number, since it is larger than the sum of its proper divisors (1).

36815981 is an equidigital number, since it uses as much as digits as its factorization.

36815981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 41.

The square root of 36815981 is about 6067.6174071871. The cubic root of 36815981 is about 332.6688414541.

The spelling of 36815981 in words is "thirty-six million, eight hundred fifteen thousand, nine hundred eighty-one".