21681084707 has 2 divisors, whose sum is σ = 21681084708. Its totient is φ = 21681084706.

The previous prime is 21681084679. The next prime is 21681084709. The reversal of 21681084707 is 70748018612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21681084707 - 2⁶ = 21681084643 is a prime.

Together with 21681084709, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21681084709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10840542353 + 10840542354.

It is an arithmetic number, because the mean of its divisors is an integer number (10840542354).

Almost surely, 2^21681084707 is an apocalyptic number.

21681084707 is a deficient number, since it is larger than the sum of its proper divisors (1).

21681084707 is an equidigital number, since it uses as much as digits as its factorization.

21681084707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 150528, while the sum is 44.

The spelling of 21681084707 in words is "twenty-one billion, six hundred eighty-one million, eighty-four thousand, seven hundred seven".