40401981 has 6 divisors (see below), whose sum is σ = 58358430. Its totient is φ = 26934648.

The previous prime is 40401973. The next prime is 40401989. The reversal of 40401981 is 18910404.

It is an interprime number because it is at equal distance from previous prime (40401973) and next prime (40401989).

It can be written as a sum of positive squares in only one way, i.e., 27657081 + 12744900 = 5259^2 + 3570^2 .

It is not a de Polignac number, because 40401981 - 2³ = 40401973 is a prime.

It is a super-2 number, since 2×40401981² = 3264640137448722, 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 (40401989) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2244546 + ... + 2244563.

It is an arithmetic number, because the mean of its divisors is an integer number (9726405).

Almost surely, 2^40401981 is an apocalyptic number.

It is an amenable number.

40401981 is a deficient number, since it is larger than the sum of its proper divisors (17956449).

40401981 is a wasteful number, since it uses less digits than its factorization.

40401981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4489115 (or 4489112 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 40401981 is about 6356.2552654845. The cubic root of 40401981 is about 343.1370026757.

The spelling of 40401981 in words is "forty million, four hundred one thousand, nine hundred eighty-one".