21601215 has 16 divisors (see below), whose sum is σ = 38402400. Its totient is φ = 11520576.

The previous prime is 21601189. The next prime is 21601277. The reversal of 21601215 is 51210612.

It is not a de Polignac number, because 21601215 - 2¹⁰ = 21600191 is a prime.

It is a super-2 number, since 2×21601215² = 933224978952450, which contains 22 as substring.

It is a plaindrome in base 16.

It is a zygodrome in base 3.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79870 + ... + 80139.

It is an arithmetic number, because the mean of its divisors is an integer number (2400150).

Almost surely, 2^21601215 is an apocalyptic number.

21601215 is a deficient number, since it is larger than the sum of its proper divisors (16801185).

21601215 is a wasteful number, since it uses less digits than its factorization.

21601215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160023 (or 160017 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21601215 is about 4647.7107267987. The cubic root of 21601215 is about 278.5005517063.

Adding to 21601215 its reverse (51210612), we get a palindrome (72811827).

It can be divided in two parts, 2160 and 1215, that multiplied together give a square (2624400 = 1620²).

The spelling of 21601215 in words is "twenty-one million, six hundred one thousand, two hundred fifteen".