21686694619 has 2 divisors, whose sum is σ = 21686694620. Its totient is φ = 21686694618.

The previous prime is 21686694571. The next prime is 21686694647. The reversal of 21686694619 is 91649668612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21686694619 is a prime.

It is a super-2 number, since 2×21686694619² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21686614619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10843347309 + 10843347310.

It is an arithmetic number, because the mean of its divisors is an integer number (10843347310).

Almost surely, 2^21686694619 is an apocalyptic number.

21686694619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21686694619 is an equidigital number, since it uses as much as digits as its factorization.

21686694619 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6718464, while the sum is 58.

The spelling of 21686694619 in words is "twenty-one billion, six hundred eighty-six million, six hundred ninety-four thousand, six hundred nineteen".