21620169 has 16 divisors (see below), whose sum is σ = 32557440. Its totient is φ = 14176080.

The previous prime is 21620153. The next prime is 21620189. The reversal of 21620169 is 96102612.

21620169 is a `hidden beast` number, since 21 + 620 + 16 + 9 = 666.

It is not a de Polignac number, because 21620169 - 2⁴ = 21620153 is a prime.

It is a super-2 number, since 2×21620169² = 934863415177122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21620129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4917 + ... + 8210.

It is an arithmetic number, because the mean of its divisors is an integer number (2034840).

Almost surely, 2^21620169 is an apocalyptic number.

It is an amenable number.

21620169 is a deficient number, since it is larger than the sum of its proper divisors (10937271).

21620169 is a wasteful number, since it uses less digits than its factorization.

21620169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13197 (or 13191 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21620169 is about 4649.7493480832. The cubic root of 21620169 is about 278.5819847226.

The spelling of 21620169 in words is "twenty-one million, six hundred twenty thousand, one hundred sixty-nine".