16668421 has 16 divisors (see below), whose sum is σ = 21454848. Its totient is φ = 12567600.

The previous prime is 16668419. The next prime is 16668451. The reversal of 16668421 is 12486661.

It is a cyclic number.

It is not a de Polignac number, because 16668421 - 2¹ = 16668419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16668401) 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, 1105 + ... + 5878.

It is an arithmetic number, because the mean of its divisors is an integer number (1340928).

Almost surely, 2^16668421 is an apocalyptic number.

16668421 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16668421 is a deficient number, since it is larger than the sum of its proper divisors (4786427).

16668421 is a wasteful number, since it uses less digits than its factorization.

16668421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7032.

The product of its digits is 13824, while the sum is 34.

The square root of 16668421 is about 4082.6977600601. The cubic root of 16668421 is about 255.4454395646.

The spelling of 16668421 in words is "sixteen million, six hundred sixty-eight thousand, four hundred twenty-one".