40138781 has 4 divisors (see below), whose sum is σ = 40363200. Its totient is φ = 39914364.

The previous prime is 40138771. The next prime is 40138801. The reversal of 40138781 is 18783104.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40138781 is a prime.

It is a super-2 number, since 2×40138781² = 3222243480331922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40138711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111941 + ... + 112298.

It is an arithmetic number, because the mean of its divisors is an integer number (10090800).

Almost surely, 2^40138781 is an apocalyptic number.

It is an amenable number.

40138781 is a deficient number, since it is larger than the sum of its proper divisors (224419).

40138781 is a wasteful number, since it uses less digits than its factorization.

40138781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224418.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 40138781 is about 6335.5174216476. The cubic root of 40138781 is about 342.3902530789.

The spelling of 40138781 in words is "forty million, one hundred thirty-eight thousand, seven hundred eighty-one".