21521169 has 12 divisors (see below), whose sum is σ = 32438016. Its totient is φ = 13723512.

The previous prime is 21521141. The next prime is 21521183. The reversal of 21521169 is 96112512.

It is not a de Polignac number, because 21521169 - 2⁷ = 21521041 is a prime.

It is a super-2 number, since 2×21521169² = 926321430253122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21521369) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 51777 + ... + 52190.

It is an arithmetic number, because the mean of its divisors is an integer number (2703168).

Almost surely, 2^21521169 is an apocalyptic number.

It is an amenable number.

21521169 is a deficient number, since it is larger than the sum of its proper divisors (10916847).

21521169 is a wasteful number, since it uses less digits than its factorization.

21521169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103996 (or 103993 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21521169 is about 4639.0913981080. The cubic root of 21521169 is about 278.1561197178.

It can be divided in two parts, 2152 and 1169, that added together give a triangular number (3321 = T₈₁).

The spelling of 21521169 in words is "twenty-one million, five hundred twenty-one thousand, one hundred sixty-nine".