21153324251 has 4 divisors (see below), whose sum is σ = 21153623400. Its totient is φ = 21153025104.

The previous prime is 21153324223. The next prime is 21153324259. The reversal of 21153324251 is 15242335112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21153324251 - 2³⁰ = 20079582427 is a prime.

It is a super-2 number, since 2×21153324251² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21153324259) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22415 + ... + 206903.

It is an arithmetic number, because the mean of its divisors is an integer number (5288405850).

Almost surely, 2^21153324251 is an apocalyptic number.

21153324251 is a deficient number, since it is larger than the sum of its proper divisors (299149).

21153324251 is a wasteful number, since it uses less digits than its factorization.

21153324251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299148.

The product of its digits is 7200, while the sum is 29.

Adding to 21153324251 its reverse (15242335112), we get a palindrome (36395659363).

The spelling of 21153324251 in words is "twenty-one billion, one hundred fifty-three million, three hundred twenty-four thousand, two hundred fifty-one".