21131133251 has 4 divisors (see below), whose sum is σ = 21186888600. Its totient is φ = 21075377904.

The previous prime is 21131133223. The next prime is 21131133269. The reversal of 21131133251 is 15233113112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21131133251 - 2⁶ = 21131133187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21131133211) 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, 27877106 + ... + 27877863.

It is an arithmetic number, because the mean of its divisors is an integer number (5296722150).

Almost surely, 2^21131133251 is an apocalyptic number.

21131133251 is a deficient number, since it is larger than the sum of its proper divisors (55755349).

21131133251 is an equidigital number, since it uses as much as digits as its factorization.

21131133251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55755348.

The product of its digits is 540, while the sum is 23.

Adding to 21131133251 its reverse (15233113112), we get a palindrome (36364246363).

The spelling of 21131133251 in words is "twenty-one billion, one hundred thirty-one million, one hundred thirty-three thousand, two hundred fifty-one".