21473717687 has 2 divisors, whose sum is σ = 21473717688. Its totient is φ = 21473717686.

The previous prime is 21473717647. The next prime is 21473717761. The reversal of 21473717687 is 78671737412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21473717687 - 2¹⁴ = 21473701303 is a prime.

It is a super-2 number, since 2×21473717687² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21473717627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10736858843 + 10736858844.

It is an arithmetic number, because the mean of its divisors is an integer number (10736858844).

Almost surely, 2^21473717687 is an apocalyptic number.

21473717687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21473717687 is an equidigital number, since it uses as much as digits as its factorization.

21473717687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2765952, while the sum is 53.

The spelling of 21473717687 in words is "twenty-one billion, four hundred seventy-three million, seven hundred seventeen thousand, six hundred eighty-seven".