21951988571 has 2 divisors, whose sum is σ = 21951988572. Its totient is φ = 21951988570.

The previous prime is 21951988559. The next prime is 21951988621. The reversal of 21951988571 is 17588915912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21951988571 - 2¹⁴ = 21951972187 is a prime.

It is not a weakly prime, because it can be changed into another prime (21951988501) 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, 10975994285 + 10975994286.

It is an arithmetic number, because the mean of its divisors is an integer number (10975994286).

Almost surely, 2^21951988571 is an apocalyptic number.

21951988571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21951988571 is an equidigital number, since it uses as much as digits as its factorization.

21951988571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1814400, while the sum is 56.

The spelling of 21951988571 in words is "twenty-one billion, nine hundred fifty-one million, nine hundred eighty-eight thousand, five hundred seventy-one".