21345121 has 8 divisors (see below), whose sum is σ = 24455744. Its totient is φ = 18249840.

The previous prime is 21345119. The next prime is 21345187. The reversal of 21345121 is 12154312.

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

It is not a de Polignac number, because 21345121 - 2¹ = 21345119 is a prime.

It is a super-2 number, since 2×21345121² = 911228381009282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21345101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 675 + ... + 6568.

It is an arithmetic number, because the mean of its divisors is an integer number (3056968).

Almost surely, 2^21345121 is an apocalyptic number.

It is an amenable number.

21345121 is a deficient number, since it is larger than the sum of its proper divisors (3110623).

21345121 is an equidigital number, since it uses as much as digits as its factorization.

21345121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7671.

The product of its digits is 240, while the sum is 19.

The square root of 21345121 is about 4620.0780296441. The cubic root of 21345121 is about 277.3955822821.

Adding to 21345121 its reverse (12154312), we get a palindrome (33499433).

The spelling of 21345121 in words is "twenty-one million, three hundred forty-five thousand, one hundred twenty-one".