21524412121 has 2 divisors, whose sum is σ = 21524412122. Its totient is φ = 21524412120.

The previous prime is 21524412109. The next prime is 21524412157. The reversal of 21524412121 is 12121442512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21443502096 + 80910025 = 146436^2 + 8995^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21524412121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21524412191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10762206060 + 10762206061.

It is an arithmetic number, because the mean of its divisors is an integer number (10762206061).

Almost surely, 2^21524412121 is an apocalyptic number.

It is an amenable number.

21524412121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21524412121 is an equidigital number, since it uses as much as digits as its factorization.

21524412121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1280, while the sum is 25.

Adding to 21524412121 its reverse (12121442512), we get a palindrome (33645854633).

The spelling of 21524412121 in words is "twenty-one billion, five hundred twenty-four million, four hundred twelve thousand, one hundred twenty-one".