21210023251 has 2 divisors, whose sum is σ = 21210023252. Its totient is φ = 21210023250.

The previous prime is 21210023143. The next prime is 21210023279. The reversal of 21210023251 is 15232001212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21210023251 - 2¹⁹ = 21209498963 is a prime.

It is not a weakly prime, because it can be changed into another prime (21210023651) 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, 10605011625 + 10605011626.

It is an arithmetic number, because the mean of its divisors is an integer number (10605011626).

Almost surely, 2^21210023251 is an apocalyptic number.

21210023251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210023251 is an equidigital number, since it uses as much as digits as its factorization.

21210023251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21210023251 its reverse (15232001212), we get a palindrome (36442024463).

The spelling of 21210023251 in words is "twenty-one billion, two hundred ten million, twenty-three thousand, two hundred fifty-one".