21158669 has 4 divisors (see below), whose sum is σ = 24181344. Its totient is φ = 18135996.

The previous prime is 21158633. The next prime is 21158671. The reversal of 21158669 is 96685112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21158669 - 2²⁴ = 4381453 is a prime.

It is a super-2 number, since 2×21158669² = 895378547703122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1511327 + ... + 1511340.

It is an arithmetic number, because the mean of its divisors is an integer number (6045336).

Almost surely, 2^21158669 is an apocalyptic number.

It is an amenable number.

21158669 is a deficient number, since it is larger than the sum of its proper divisors (3022675).

21158669 is an equidigital number, since it uses as much as digits as its factorization.

21158669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3022674.

The product of its digits is 25920, while the sum is 38.

The square root of 21158669 is about 4599.8553238118. The cubic root of 21158669 is about 276.5855253091.

The spelling of 21158669 in words is "twenty-one million, one hundred fifty-eight thousand, six hundred sixty-nine".