21320313251 has 2 divisors, whose sum is σ = 21320313252. Its totient is φ = 21320313250.

The previous prime is 21320313239. The next prime is 21320313263. The reversal of 21320313251 is 15231302312.

It is a balanced prime because it is at equal distance from previous prime (21320313239) and next prime (21320313263).

It is a cyclic number.

It is not a de Polignac number, because 21320313251 - 2⁶ = 21320313187 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21320313211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660156625 + 10660156626.

It is an arithmetic number, because the mean of its divisors is an integer number (10660156626).

Almost surely, 2^21320313251 is an apocalyptic number.

21320313251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320313251 is an equidigital number, since it uses as much as digits as its factorization.

21320313251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 23.

Adding to 21320313251 its reverse (15231302312), we get a palindrome (36551615563).

The spelling of 21320313251 in words is "twenty-one billion, three hundred twenty million, three hundred thirteen thousand, two hundred fifty-one".