16621989 has 8 divisors (see below), whose sum is σ = 22249920. Its totient is φ = 11037696.

The previous prime is 16621967. The next prime is 16622009. The reversal of 16621989 is 98912661.

16621989 = 1355² + 1356² + ... + 1363².

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16621989 - 2⁹ = 16621477 is a prime.

It is a super-2 number, since 2×16621989² = 552581036632242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16621989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16621949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10009 + ... + 11550.

It is an arithmetic number, because the mean of its divisors is an integer number (2781240).

Almost surely, 2^16621989 is an apocalyptic number.

It is an amenable number.

16621989 is a deficient number, since it is larger than the sum of its proper divisors (5627931).

16621989 is a wasteful number, since it uses less digits than its factorization.

16621989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21819.

The product of its digits is 46656, while the sum is 42.

The square root of 16621989 is about 4077.0073583451. The cubic root of 16621989 is about 255.2080270943.

It can be divided in two parts, 166 and 21989, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 16621989 in words is "sixteen million, six hundred twenty-one thousand, nine hundred eighty-nine".