16447721 has 16 divisors (see below), whose sum is σ = 18167040. Its totient is φ = 14826240.

The previous prime is 16447699. The next prime is 16447723. The reversal of 16447721 is 12774461.

It is a cyclic number.

It is not a de Polignac number, because 16447721 - 2⁶ = 16447657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16447723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49526 + ... + 49856.

It is an arithmetic number, because the mean of its divisors is an integer number (1135440).

Almost surely, 2^16447721 is an apocalyptic number.

It is an amenable number.

16447721 is a deficient number, since it is larger than the sum of its proper divisors (1719319).

16447721 is a wasteful number, since it uses less digits than its factorization.

16447721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 464.

The product of its digits is 9408, while the sum is 32.

The square root of 16447721 is about 4055.5789968881. The cubic root of 16447721 is about 254.3130092408.

The spelling of 16447721 in words is "sixteen million, four hundred forty-seven thousand, seven hundred twenty-one".