16721973 has 12 divisors (see below), whose sum is σ = 24743628. Its totient is φ = 10875840.

The previous prime is 16721953. The next prime is 16721981. The reversal of 16721973 is 37912761.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 3017169 + 13704804 = 1737^2 + 3702^2 .

It is not a de Polignac number, because 16721973 - 2⁵ = 16721941 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16721923) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22290 + ... + 23027.

It is an arithmetic number, because the mean of its divisors is an integer number (2061969).

Almost surely, 2^16721973 is an apocalyptic number.

It is an amenable number.

16721973 is a deficient number, since it is larger than the sum of its proper divisors (8021655).

16721973 is a wasteful number, since it uses less digits than its factorization.

16721973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45364 (or 45361 counting only the distinct ones).

The product of its digits is 15876, while the sum is 36.

The square root of 16721973 is about 4089.2509093965. The cubic root of 16721973 is about 255.7187106081.

The spelling of 16721973 in words is "sixteen million, seven hundred twenty-one thousand, nine hundred seventy-three".