21316751 has 2 divisors, whose sum is σ = 21316752. Its totient is φ = 21316750.

The previous prime is 21316741. The next prime is 21316753. The reversal of 21316751 is 15761312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21316751 is a prime.

Together with 21316753, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21316751.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21316753) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10658375 + 10658376.

It is an arithmetic number, because the mean of its divisors is an integer number (10658376).

Almost surely, 2^21316751 is an apocalyptic number.

21316751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21316751 is an equidigital number, since it uses as much as digits as its factorization.

21316751 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1260, while the sum is 26.

The square root of 21316751 is about 4617.0067143118. The cubic root of 21316751 is about 277.2726314399.

The spelling of 21316751 in words is "twenty-one million, three hundred sixteen thousand, seven hundred fifty-one".