40408721 has 4 divisors (see below), whose sum is σ = 40551792. Its totient is φ = 40265652.

The previous prime is 40408703. The next prime is 40408751. The reversal of 40408721 is 12780404.

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 not a de Polignac number, because 40408721 - 2¹⁸ = 40146577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40408751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71111 + ... + 71676.

It is an arithmetic number, because the mean of its divisors is an integer number (10137948).

Almost surely, 2^40408721 is an apocalyptic number.

It is an amenable number.

40408721 is a deficient number, since it is larger than the sum of its proper divisors (143071).

40408721 is a wasteful number, since it uses less digits than its factorization.

40408721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143070.

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 40408721 is about 6356.7854297593. The cubic root of 40408721 is about 343.1560827203.

The spelling of 40408721 in words is "forty million, four hundred eight thousand, seven hundred twenty-one".