21894691361 has 2 divisors, whose sum is σ = 21894691362. Its totient is φ = 21894691360.

The previous prime is 21894691321. The next prime is 21894691393. The reversal of 21894691361 is 16319649812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12953854225 + 8940837136 = 113815^2 + 94556^2 .

It is a cyclic number.

It is not a de Polignac number, because 21894691361 - 2⁶ = 21894691297 is a prime.

It is not a weakly prime, because it can be changed into another prime (21894691321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10947345680 + 10947345681.

It is an arithmetic number, because the mean of its divisors is an integer number (10947345681).

Almost surely, 2^21894691361 is an apocalyptic number.

It is an amenable number.

21894691361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21894691361 is an equidigital number, since it uses as much as digits as its factorization.

21894691361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 559872, while the sum is 50.

The spelling of 21894691361 in words is "twenty-one billion, eight hundred ninety-four million, six hundred ninety-one thousand, three hundred sixty-one".