21999999999997 has 2 divisors, whose sum is σ = 21999999999998. Its totient is φ = 21999999999996.

The previous prime is 21999999999917. The next prime is 22000000000009. The reversal of 21999999999997 is 79999999999912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17705866971556 + 4294133028441 = 4207834^2 + 2072229^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21999999999997 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21999999999893 and 21999999999902.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21999999999917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999999999998 + 10999999999999.

It is an arithmetic number, because the mean of its divisors is an integer number (10999999999999).

Almost surely, 2^{21999999999997} is an apocalyptic number.

It is an amenable number.

21999999999997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21999999999997 is an equidigital number, since it uses as much as digits as its factorization.

21999999999997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 439334834526, while the sum is 109.

The spelling of 21999999999997 in words is "twenty-one trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-seven".