21081423247 has 2 divisors, whose sum is σ = 21081423248. Its totient is φ = 21081423246.

The previous prime is 21081423227. The next prime is 21081423271. The reversal of 21081423247 is 74232418012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21081423247 is a prime.

It is a super-2 number, since 2×21081423247² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21081423227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10540711623 + 10540711624.

It is an arithmetic number, because the mean of its divisors is an integer number (10540711624).

Almost surely, 2^21081423247 is an apocalyptic number.

21081423247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21081423247 is an equidigital number, since it uses as much as digits as its factorization.

21081423247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21504, while the sum is 34.

The spelling of 21081423247 in words is "twenty-one billion, eighty-one million, four hundred twenty-three thousand, two hundred forty-seven".