21597121 has 8 divisors (see below), whose sum is σ = 26581184. Its totient is φ = 17087760.

The previous prime is 21597113. The next prime is 21597131. The reversal of 21597121 is 12179512.

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

It is a cyclic number.

It is not a de Polignac number, because 21597121 - 2³ = 21597113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21597121.

It is not an unprimeable number, because it can be changed into a prime (21597131) 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 7 ways as a sum of consecutive naturals, for example, 118575 + ... + 118756.

It is an arithmetic number, because the mean of its divisors is an integer number (3322648).

Almost surely, 2^21597121 is an apocalyptic number.

It is an amenable number.

21597121 is a deficient number, since it is larger than the sum of its proper divisors (4984063).

21597121 is a wasteful number, since it uses less digits than its factorization.

21597121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237351.

The product of its digits is 1260, while the sum is 28.

The square root of 21597121 is about 4647.2702740426. The cubic root of 21597121 is about 278.4829561945.

It can be divided in two parts, 215 and 97121, that added together give a cube (97336 = 46³).

The spelling of 21597121 in words is "twenty-one million, five hundred ninety-seven thousand, one hundred twenty-one".