16861421 has 4 divisors (see below), whose sum is σ = 17113152. Its totient is φ = 16609692.

The previous prime is 16861387. The next prime is 16861447. The reversal of 16861421 is 12416861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12416861 = 19 ⋅653519.

It is a cyclic number.

It is not a de Polignac number, because 16861421 - 2⁶ = 16861357 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 (16861451) 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, 125765 + ... + 125898.

It is an arithmetic number, because the mean of its divisors is an integer number (4278288).

Almost surely, 2^16861421 is an apocalyptic number.

It is an amenable number.

16861421 is a deficient number, since it is larger than the sum of its proper divisors (251731).

16861421 is an equidigital number, since it uses as much as digits as its factorization.

16861421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251730.

The product of its digits is 2304, while the sum is 29.

The square root of 16861421 is about 4106.2660654176. The cubic root of 16861421 is about 256.4275742405.

The spelling of 16861421 in words is "sixteen million, eight hundred sixty-one thousand, four hundred twenty-one".