16751921 has 4 divisors (see below), whose sum is σ = 16864500. Its totient is φ = 16639344.

The previous prime is 16751909. The next prime is 16751927. The reversal of 16751921 is 12915761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12915761 = 587 ⋅22003.

It can be written as a sum of positive squares in 2 ways, for example, as 6760000 + 9991921 = 2600^2 + 3161^2 .

It is a cyclic number.

It is not a de Polignac number, because 16751921 - 2⁶ = 16751857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16751927) 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, 56066 + ... + 56363.

It is an arithmetic number, because the mean of its divisors is an integer number (4216125).

Almost surely, 2^16751921 is an apocalyptic number.

It is an amenable number.

16751921 is a deficient number, since it is larger than the sum of its proper divisors (112579).

16751921 is a wasteful number, since it uses less digits than its factorization.

16751921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112578.

The product of its digits is 3780, while the sum is 32.

The square root of 16751921 is about 4092.9110667103. The cubic root of 16751921 is about 255.8712782640.

The spelling of 16751921 in words is "sixteen million, seven hundred fifty-one thousand, nine hundred twenty-one".