21657369 has 8 divisors (see below), whose sum is σ = 29022400. Its totient is φ = 14365296.

The previous prime is 21657367. The next prime is 21657401. The reversal of 21657369 is 96375612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21657369 - 2¹ = 21657367 is a prime.

It is a super-2 number, since 2×21657369² = 938083264004322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21657367) 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 7 ways as a sum of consecutive naturals, for example, 17542 + ... + 18735.

It is an arithmetic number, because the mean of its divisors is an integer number (3627800).

Almost surely, 2^21657369 is an apocalyptic number.

It is an amenable number.

21657369 is a deficient number, since it is larger than the sum of its proper divisors (7365031).

21657369 is a wasteful number, since it uses less digits than its factorization.

21657369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36479.

The product of its digits is 68040, while the sum is 39.

The square root of 21657369 is about 4653.7478444798. The cubic root of 21657369 is about 278.7416706742.

The spelling of 21657369 in words is "twenty-one million, six hundred fifty-seven thousand, three hundred sixty-nine".