21601015 has 8 divisors (see below), whose sum is σ = 26346528. Its totient is φ = 16997280.

The previous prime is 21600991. The next prime is 21601061. The reversal of 21601015 is 51010612.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-21601015 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21601015.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35107 + ... + 35716.

It is an arithmetic number, because the mean of its divisors is an integer number (3293316).

Almost surely, 2^21601015 is an apocalyptic number.

21601015 is a deficient number, since it is larger than the sum of its proper divisors (4745513).

21601015 is an equidigital number, since it uses as much as digits as its factorization.

21601015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70889.

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 21601015 is about 4647.6892107799. The cubic root of 21601015 is about 278.4996921824.

Adding to 21601015 its reverse (51010612), we get a palindrome (72611627).

The spelling of 21601015 in words is "twenty-one million, six hundred one thousand, fifteen".