21642221371 has 2 divisors, whose sum is σ = 21642221372. Its totient is φ = 21642221370.

The previous prime is 21642221333. The next prime is 21642221383. The reversal of 21642221371 is 17312224612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21642221371 is a prime.

It is not a weakly prime, because it can be changed into another prime (21642228371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821110685 + 10821110686.

It is an arithmetic number, because the mean of its divisors is an integer number (10821110686).

Almost surely, 2^21642221371 is an apocalyptic number.

21642221371 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642221371 is an equidigital number, since it uses as much as digits as its factorization.

21642221371 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 31.

Adding to 21642221371 its reverse (17312224612), we get a palindrome (38954445983).

The spelling of 21642221371 in words is "twenty-one billion, six hundred forty-two million, two hundred twenty-one thousand, three hundred seventy-one".