21620121 has 8 divisors (see below), whose sum is σ = 28858464. Its totient is φ = 14397600.

The previous prime is 21620117. The next prime is 21620129. The reversal of 21620121 is 12102612.

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

It is not a de Polignac number, because 21620121 - 2² = 21620117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21620121.

It is not an unprimeable number, because it can be changed into a prime (21620129) 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, 276 + ... + 6581.

It is an arithmetic number, because the mean of its divisors is an integer number (3607308).

Almost surely, 2^21620121 is an apocalyptic number.

It is an amenable number.

21620121 is a deficient number, since it is larger than the sum of its proper divisors (7238343).

21620121 is a wasteful number, since it uses less digits than its factorization.

21620121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7911.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21620121 is about 4649.7441865118. The cubic root of 21620121 is about 278.5817785579.

Adding to 21620121 its reverse (12102612), we get a palindrome (33722733).

The spelling of 21620121 in words is "twenty-one million, six hundred twenty thousand, one hundred twenty-one".