40128781 has 8 divisors (see below), whose sum is σ = 50030784. Its totient is φ = 31269120.

The previous prime is 40128773. The next prime is 40128793. The reversal of 40128781 is 18782104.

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 40128781 - 2³ = 40128773 is a prime.

It is a super-2 number, since 2×40128781² = 3220638129091922, 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 (40128701) 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, 260500 + ... + 260653.

It is an arithmetic number, because the mean of its divisors is an integer number (6253848).

Almost surely, 2^40128781 is an apocalyptic number.

It is an amenable number.

40128781 is a deficient number, since it is larger than the sum of its proper divisors (9902003).

40128781 is a wasteful number, since it uses less digits than its factorization.

40128781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521171.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 40128781 is about 6334.7281709636. The cubic root of 40128781 is about 342.3618168482.

It can be divided in two parts, 40 and 128781, that added together give a palindrome (128821).

The spelling of 40128781 in words is "forty million, one hundred twenty-eight thousand, seven hundred eighty-one".