16921945 has 4 divisors (see below), whose sum is σ = 20306340. Its totient is φ = 13537552.

The previous prime is 16921937. The next prime is 16921969. The reversal of 16921945 is 54912961.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3810304 + 13111641 = 1952^2 + 3621^2 .

It is a cyclic number.

It is not a de Polignac number, because 16921945 - 2³ = 16921937 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1692190 + ... + 1692199.

It is an arithmetic number, because the mean of its divisors is an integer number (5076585).

Almost surely, 2^16921945 is an apocalyptic number.

It is an amenable number.

16921945 is a deficient number, since it is larger than the sum of its proper divisors (3384395).

16921945 is an equidigital number, since it uses as much as digits as its factorization.

16921945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3384394.

The product of its digits is 19440, while the sum is 37.

The square root of 16921945 is about 4113.6291762870. The cubic root of 16921945 is about 256.7340231011.

The spelling of 16921945 in words is "sixteen million, nine hundred twenty-one thousand, nine hundred forty-five".