21413121 has 16 divisors (see below), whose sum is σ = 29457600. Its totient is φ = 13825728.

The previous prime is 21413101. The next prime is 21413123. The reversal of 21413121 is 12131412.

It is not a de Polignac number, because 21413121 - 2¹⁷ = 21282049 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21413121.

It is not an unprimeable number, because it can be changed into a prime (21413123) 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 15 ways as a sum of consecutive naturals, for example, 41815 + ... + 42323.

It is an arithmetic number, because the mean of its divisors is an integer number (1841100).

Almost surely, 2^21413121 is an apocalyptic number.

It is an amenable number.

21413121 is a deficient number, since it is larger than the sum of its proper divisors (8044479).

21413121 is a wasteful number, since it uses less digits than its factorization.

21413121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 928.

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

The square root of 21413121 is about 4627.4313609172. The cubic root of 21413121 is about 277.6898400692.

Adding to 21413121 its reverse (12131412), we get a palindrome (33544533).

The spelling of 21413121 in words is "twenty-one million, four hundred thirteen thousand, one hundred twenty-one".