21012169 has 4 divisors (see below), whose sum is σ = 21024900. Its totient is φ = 20999440.

The previous prime is 21012161. The next prime is 21012181. The reversal of 21012169 is 96121012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11648569 + 9363600 = 3413^2 + 3060^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012169 - 2³ = 21012161 is a prime.

It is a super-2 number, since 2×21012169² = 883022492169122, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3442 + ... + 7339.

It is an arithmetic number, because the mean of its divisors is an integer number (5256225).

Almost surely, 2^21012169 is an apocalyptic number.

It is an amenable number.

21012169 is a deficient number, since it is larger than the sum of its proper divisors (12731).

21012169 is a wasteful number, since it uses less digits than its factorization.

21012169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12730.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 21012169 is about 4583.9032494153. The cubic root of 21012169 is about 275.9456983768.

The spelling of 21012169 in words is "twenty-one million, twelve thousand, one hundred sixty-nine".