40405981 has 16 divisors (see below), whose sum is σ = 51331968. Its totient is φ = 30888000.

The previous prime is 40405931. The next prime is 40405987. The reversal of 40405981 is 18950404.

It is a happy number.

It is not a de Polignac number, because 40405981 - 2¹¹ = 40403933 is a prime.

It is a super-2 number, since 2×40405981² = 3265286601144722, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40405987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 870 + ... + 9031.

It is an arithmetic number, because the mean of its divisors is an integer number (3208248).

Almost surely, 2^40405981 is an apocalyptic number.

It is an amenable number.

40405981 is a deficient number, since it is larger than the sum of its proper divisors (10925987).

40405981 is a wasteful number, since it uses less digits than its factorization.

40405981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9972.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 40405981 is about 6356.5699083704. The cubic root of 40405981 is about 343.1483264003.

The spelling of 40405981 in words is "forty million, four hundred five thousand, nine hundred eighty-one".