40215921 has 4 divisors (see below), whose sum is σ = 53621232. Its totient is φ = 26810612.

The previous prime is 40215899. The next prime is 40215949. The reversal of 40215921 is 12951204.

40215921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 40215921 - 2¹⁸ = 39953777 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 40215891 and 40215900.

It is not an unprimeable number, because it can be changed into a prime (40215971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6702651 + ... + 6702656.

It is an arithmetic number, because the mean of its divisors is an integer number (13405308).

Almost surely, 2^40215921 is an apocalyptic number.

It is an amenable number.

40215921 is a deficient number, since it is larger than the sum of its proper divisors (13405311).

40215921 is a wasteful number, since it uses less digits than its factorization.

40215921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13405310.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 40215921 is about 6341.6024000248. The cubic root of 40215921 is about 342.6094515839.

The spelling of 40215921 in words is "forty million, two hundred fifteen thousand, nine hundred twenty-one".