21345306251 has 2 divisors, whose sum is σ = 21345306252. Its totient is φ = 21345306250.

The previous prime is 21345306221. The next prime is 21345306313. The reversal of 21345306251 is 15260354312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21345306251 - 2²⁶ = 21278197387 is a prime.

It is not a weakly prime, because it can be changed into another prime (21345306221) 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 as a sum of consecutive naturals, namely, 10672653125 + 10672653126.

It is an arithmetic number, because the mean of its divisors is an integer number (10672653126).

Almost surely, 2^21345306251 is an apocalyptic number.

21345306251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21345306251 is an equidigital number, since it uses as much as digits as its factorization.

21345306251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21600, while the sum is 32.

The spelling of 21345306251 in words is "twenty-one billion, three hundred forty-five million, three hundred six thousand, two hundred fifty-one".