21289820971 has 2 divisors, whose sum is σ = 21289820972. Its totient is φ = 21289820970.

The previous prime is 21289820969. The next prime is 21289820983. The reversal of 21289820971 is 17902898212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21289820971 - 2¹ = 21289820969 is a prime.

Together with 21289820969, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21289829971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10644910485 + 10644910486.

It is an arithmetic number, because the mean of its divisors is an integer number (10644910486).

Almost surely, 2^21289820971 is an apocalyptic number.

21289820971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21289820971 is an equidigital number, since it uses as much as digits as its factorization.

21289820971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 290304, while the sum is 49.

The spelling of 21289820971 in words is "twenty-one billion, two hundred eighty-nine million, eight hundred twenty thousand, nine hundred seventy-one".