21251234213 has 4 divisors (see below), whose sum is σ = 23183164608. Its totient is φ = 19319303820.

The previous prime is 21251234177. The next prime is 21251234219. The reversal of 21251234213 is 31243215212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21251234213 is a prime.

It is a super-2 number, since 2×21251234213² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251234219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 965965181 + ... + 965965202.

It is an arithmetic number, because the mean of its divisors is an integer number (5795791152).

Almost surely, 2^21251234213 is an apocalyptic number.

It is an amenable number.

21251234213 is a deficient number, since it is larger than the sum of its proper divisors (1931930395).

21251234213 is a wasteful number, since it uses less digits than its factorization.

21251234213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1931930394.

The product of its digits is 2880, while the sum is 26.

Adding to 21251234213 its reverse (31243215212), we get a palindrome (52494449425).

The spelling of 21251234213 in words is "twenty-one billion, two hundred fifty-one million, two hundred thirty-four thousand, two hundred thirteen".