21612415253 has 16 divisors (see below), whose sum is σ = 25395249600. Its totient is φ = 18133121280.

The previous prime is 21612415243. The next prime is 21612415261. The reversal of 21612415253 is 35251421612.

It is a cyclic number.

It is not a de Polignac number, because 21612415253 - 2⁶ = 21612415189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612415243) 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 15 ways as a sum of consecutive naturals, for example, 1187738 + ... + 1205796.

It is an arithmetic number, because the mean of its divisors is an integer number (1587203100).

Almost surely, 2^21612415253 is an apocalyptic number.

It is an amenable number.

21612415253 is a deficient number, since it is larger than the sum of its proper divisors (3782834347).

21612415253 is a wasteful number, since it uses less digits than its factorization.

21612415253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26452.

The product of its digits is 14400, while the sum is 32.

Adding to 21612415253 its reverse (35251421612), we get a palindrome (56863836865).

The spelling of 21612415253 in words is "twenty-one billion, six hundred twelve million, four hundred fifteen thousand, two hundred fifty-three".