21021111200251 has 2 divisors, whose sum is σ = 21021111200252. Its totient is φ = 21021111200250.

The previous prime is 21021111200087. The next prime is 21021111200261. The reversal of 21021111200251 is 15200211112012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021111200251 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021111200261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510555600125 + 10510555600126.

It is an arithmetic number, because the mean of its divisors is an integer number (10510555600126).

Almost surely, 2^{21021111200251} is an apocalyptic number.

21021111200251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021111200251 is an equidigital number, since it uses as much as digits as its factorization.

21021111200251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80, while the sum is 19.

Adding to 21021111200251 its reverse (15200211112012), we get a palindrome (36221322312263).

The spelling of 21021111200251 in words is "twenty-one trillion, twenty-one billion, one hundred eleven million, two hundred thousand, two hundred fifty-one".