21905169 has 16 divisors (see below), whose sum is σ = 34313664. Its totient is φ = 12254400.

The previous prime is 21905167. The next prime is 21905173. The reversal of 21905169 is 96150912.

It is not a de Polignac number, because 21905169 - 2¹ = 21905167 is a prime.

It is a super-2 number, since 2×21905169² = 959672857837122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21905167) 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, 25102 + ... + 25959.

It is an arithmetic number, because the mean of its divisors is an integer number (2144604).

Almost surely, 2^21905169 is an apocalyptic number.

It is an amenable number.

21905169 is a deficient number, since it is larger than the sum of its proper divisors (12408495).

21905169 is a wasteful number, since it uses less digits than its factorization.

21905169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51088.

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 21905169 is about 4680.2958239838. The cubic root of 21905169 is about 279.8007468469.

The spelling of 21905169 in words is "twenty-one million, nine hundred five thousand, one hundred sixty-nine".