38591981 has 2 divisors, whose sum is σ = 38591982. Its totient is φ = 38591980.

The previous prime is 38591963. The next prime is 38592007. The reversal of 38591981 is 18919583.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34409956 + 4182025 = 5866^2 + 2045^2 .

It is a cyclic number.

It is not a de Polignac number, because 38591981 - 2²² = 34397677 is a prime.

It is a super-2 number, since 2×38591981² = 2978681995008722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (38591951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19295990 + 19295991.

It is an arithmetic number, because the mean of its divisors is an integer number (19295991).

Almost surely, 2^38591981 is an apocalyptic number.

It is an amenable number.

38591981 is a deficient number, since it is larger than the sum of its proper divisors (1).

38591981 is an equidigital number, since it uses as much as digits as its factorization.

38591981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 44.

The square root of 38591981 is about 6212.2444414237. The cubic root of 38591981 is about 337.9343645529.

It can be divided in two parts, 38 and 591981, that multiplied together give a triangular number (22495278 = T₆₇₀₇).

The spelling of 38591981 in words is "thirty-eight million, five hundred ninety-one thousand, nine hundred eighty-one".