21251235013 has 4 divisors (see below), whose sum is σ = 21252313888. Its totient is φ = 21250156140.

The previous prime is 21251234947. The next prime is 21251235029. The reversal of 21251235013 is 31053215212.

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-21251235013 is a prime.

It is a super-2 number, since 2×21251235013² (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 (21251235073) 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, 509331 + ... + 549472.

It is an arithmetic number, because the mean of its divisors is an integer number (5313078472).

Almost surely, 2^21251235013 is an apocalyptic number.

It is an amenable number.

21251235013 is a deficient number, since it is larger than the sum of its proper divisors (1078875).

21251235013 is a wasteful number, since it uses less digits than its factorization.

21251235013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078874.

The product of its (nonzero) digits is 1800, while the sum is 25.

The spelling of 21251235013 in words is "twenty-one billion, two hundred fifty-one million, two hundred thirty-five thousand, thirteen".