40990721 has 4 divisors (see below), whose sum is σ = 41862912. Its totient is φ = 40118532.

The previous prime is 40990699. The next prime is 40990753. The reversal of 40990721 is 12709904.

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 40990721 - 2¹⁸ = 40728577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40990121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 436025 + ... + 436118.

It is an arithmetic number, because the mean of its divisors is an integer number (10465728).

Almost surely, 2^40990721 is an apocalyptic number.

It is an amenable number.

40990721 is a deficient number, since it is larger than the sum of its proper divisors (872191).

40990721 is an equidigital number, since it uses as much as digits as its factorization.

40990721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 872190.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 40990721 is about 6402.3996282644. The cubic root of 40990721 is about 344.7957090612.

The spelling of 40990721 in words is "forty million, nine hundred ninety thousand, seven hundred twenty-one".