40821721 has 4 divisors (see below), whose sum is σ = 40850944. Its totient is φ = 40792500.

The previous prime is 40821707. The next prime is 40821779. The reversal of 40821721 is 12712804.

It is a happy number.

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 40821721 - 2¹¹ = 40819673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40821701) 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, 12405 + ... + 15346.

It is an arithmetic number, because the mean of its divisors is an integer number (10212736).

Almost surely, 2^40821721 is an apocalyptic number.

It is an amenable number.

40821721 is a deficient number, since it is larger than the sum of its proper divisors (29223).

40821721 is a wasteful number, since it uses less digits than its factorization.

40821721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29222.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 40821721 is about 6389.1878200598. The cubic root of 40821721 is about 344.3212054162.

The spelling of 40821721 in words is "forty million, eight hundred twenty-one thousand, seven hundred twenty-one".