40239981 has 12 divisors (see below), whose sum is σ = 58179420. Its totient is φ = 26801280.

The previous prime is 40239971. The next prime is 40240007. The reversal of 40239981 is 18993204.

It can be written as a sum of positive squares in 2 ways, for example, as 15139881 + 25100100 = 3891^2 + 5010^2 .

It is not a de Polignac number, because 40239981 - 2⁹ = 40239469 is a prime.

It is a super-2 number, since 2×40239981² = 3238512141760722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40239911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17541 + ... + 19701.

It is an arithmetic number, because the mean of its divisors is an integer number (4848285).

Almost surely, 2^40239981 is an apocalyptic number.

It is an amenable number.

40239981 is a deficient number, since it is larger than the sum of its proper divisors (17939439).

40239981 is a wasteful number, since it uses less digits than its factorization.

40239981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4236 (or 4233 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 40239981 is about 6343.4991132655. The cubic root of 40239981 is about 342.6777623413.

The spelling of 40239981 in words is "forty million, two hundred thirty-nine thousand, nine hundred eighty-one".