21008169 has 48 divisors (see below), whose sum is σ = 37844352. Its totient is φ = 10934784.

The previous prime is 21008153. The next prime is 21008171. The reversal of 21008169 is 96180012.

It is not a de Polignac number, because 21008169 - 2⁴ = 21008153 is a prime.

It is a super-2 number, since 2×21008169² = 882686329465122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21008149) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 92434 + ... + 92660.

It is an arithmetic number, because the mean of its divisors is an integer number (788424).

Almost surely, 2^21008169 is an apocalyptic number.

It is an amenable number.

21008169 is a deficient number, since it is larger than the sum of its proper divisors (16836183).

21008169 is a wasteful number, since it uses less digits than its factorization.

21008169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 21008169 is about 4583.4669192654. The cubic root of 21008169 is about 275.9281870506.

The spelling of 21008169 in words is "twenty-one million, eight thousand, one hundred sixty-nine".