21945773987 has 2 divisors, whose sum is σ = 21945773988. Its totient is φ = 21945773986.

The previous prime is 21945773963. The next prime is 21945774049. The reversal of 21945773987 is 78937754912.

It is an a-pointer prime, because the next prime (21945774049) can be obtained adding 21945773987 to its sum of digits (62).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21945773987 - 2⁶ = 21945773923 is a prime.

It is not a weakly prime, because it can be changed into another prime (21945773917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972886993 + 10972886994.

It is an arithmetic number, because the mean of its divisors is an integer number (10972886994).

Almost surely, 2^21945773987 is an apocalyptic number.

21945773987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945773987 is an equidigital number, since it uses as much as digits as its factorization.

21945773987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26671680, while the sum is 62.

The spelling of 21945773987 in words is "twenty-one billion, nine hundred forty-five million, seven hundred seventy-three thousand, nine hundred eighty-seven".