16316721 has 24 divisors (see below), whose sum is σ = 24766560. Its totient is φ = 10733472.

The previous prime is 16316689. The next prime is 16316731. The reversal of 16316721 is 12761361.

16316721 is a `hidden beast` number, since 1 + 631 + 6 + 7 + 21 = 666.

It is not a de Polignac number, because 16316721 - 2⁵ = 16316689 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16316731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19765 + ... + 20573.

It is an arithmetic number, because the mean of its divisors is an integer number (1031940).

Almost surely, 2^16316721 is an apocalyptic number.

It is an amenable number.

16316721 is a deficient number, since it is larger than the sum of its proper divisors (8449839).

16316721 is an frugal number, since it uses more digits than its factorization.

16316721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907 (or 895 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 16316721 is about 4039.3961182335. The cubic root of 16316721 is about 253.6360391633.

The spelling of 16316721 in words is "sixteen million, three hundred sixteen thousand, seven hundred twenty-one".