40291981 has 2 divisors, whose sum is σ = 40291982. Its totient is φ = 40291980.

The previous prime is 40291973. The next prime is 40291987. The reversal of 40291981 is 18919204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38068900 + 2223081 = 6170^2 + 1491^2 .

It is a cyclic number.

It is not a de Polignac number, because 40291981 - 2³ = 40291973 is a prime.

It is a super-2 number, since 2×40291981² = 3246887465808722, which contains 22 as substring.

It is a nialpdrome in base 7.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40291987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20145990 + 20145991.

It is an arithmetic number, because the mean of its divisors is an integer number (20145991).

Almost surely, 2^40291981 is an apocalyptic number.

It is an amenable number.

40291981 is a deficient number, since it is larger than the sum of its proper divisors (1).

40291981 is an equidigital number, since it uses as much as digits as its factorization.

40291981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 40291981 is about 6347.5964742570. The cubic root of 40291981 is about 342.8253069233.

The spelling of 40291981 in words is "forty million, two hundred ninety-one thousand, nine hundred eighty-one".