40217721 has 8 divisors (see below), whose sum is σ = 53709600. Its totient is φ = 26768832.

The previous prime is 40217719. The next prime is 40217729. The reversal of 40217721 is 12771204.

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

It is not a de Polignac number, because 40217721 - 2¹ = 40217719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 40217691 and 40217700.

It is not an unprimeable number, because it can be changed into a prime (40217729) 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, 8496 + ... + 12353.

It is an arithmetic number, because the mean of its divisors is an integer number (6713700).

Almost surely, 2^40217721 is an apocalyptic number.

It is an amenable number.

40217721 is a deficient number, since it is larger than the sum of its proper divisors (13491879).

40217721 is a wasteful number, since it uses less digits than its factorization.

40217721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21495.

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 40217721 is about 6341.7443184033. The cubic root of 40217721 is about 342.6145630572.

Adding to 40217721 its reverse (12771204), we get a palindrome (52988925).

The spelling of 40217721 in words is "forty million, two hundred seventeen thousand, seven hundred twenty-one".