16409721 has 8 divisors (see below), whose sum is σ = 22345344. Its totient is φ = 10706960.

The previous prime is 16409719. The next prime is 16409753. The reversal of 16409721 is 12790461.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 16409721 - 2¹ = 16409719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16402721) 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, 58050 + ... + 58331.

It is an arithmetic number, because the mean of its divisors is an integer number (2793168).

Almost surely, 2^16409721 is an apocalyptic number.

It is an amenable number.

16409721 is a deficient number, since it is larger than the sum of its proper divisors (5935623).

16409721 is a wasteful number, since it uses less digits than its factorization.

16409721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116431.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 16409721 is about 4050.8913833871. The cubic root of 16409721 is about 254.1170074919.

The spelling of 16409721 in words is "sixteen million, four hundred nine thousand, seven hundred twenty-one".