40438781 has 8 divisors (see below), whose sum is σ = 40864824. Its totient is φ = 40015360.

The previous prime is 40438709. The next prime is 40438813. The reversal of 40438781 is 18783404.

40438781 = 103² + 104² + ... + 496².

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5522500 + 34916281 = 2350^2 + 5909^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 40438781 - 2²² = 36244477 is a prime.

It is a super-2 number, since 2×40438781² = 3270590017531922, 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 (40438081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45461 + ... + 46341.

It is an arithmetic number, because the mean of its divisors is an integer number (5108103).

Almost surely, 2^40438781 is an apocalyptic number.

It is an amenable number.

40438781 is a deficient number, since it is larger than the sum of its proper divisors (426043).

40438781 is a wasteful number, since it uses less digits than its factorization.

40438781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1311.

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 40438781 is about 6359.1493928040. The cubic root of 40438781 is about 343.2411527647.

The spelling of 40438781 in words is "forty million, four hundred thirty-eight thousand, seven hundred eighty-one".