21221201087 has 2 divisors, whose sum is σ = 21221201088. Its totient is φ = 21221201086.

The previous prime is 21221201059. The next prime is 21221201117. The reversal of 21221201087 is 78010212212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221201087 - 2⁸ = 21221200831 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221201047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610600543 + 10610600544.

It is an arithmetic number, because the mean of its divisors is an integer number (10610600544).

Almost surely, 2^21221201087 is an apocalyptic number.

21221201087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221201087 is an equidigital number, since it uses as much as digits as its factorization.

21221201087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 26.

Adding to 21221201087 its reverse (78010212212), we get a palindrome (99231413299).

The spelling of 21221201087 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, eighty-seven".