21473717761 has 2 divisors, whose sum is σ = 21473717762. Its totient is φ = 21473717760.

The previous prime is 21473717687. The next prime is 21473717789. The reversal of 21473717761 is 16771737412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20095897600 + 1377820161 = 141760^2 + 37119^2 .

It is a cyclic number.

It is not a de Polignac number, because 21473717761 - 2⁷ = 21473717633 is a prime.

It is a super-2 number, since 2×21473717761² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21473712761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10736858880 + 10736858881.

It is an arithmetic number, because the mean of its divisors is an integer number (10736858881).

Almost surely, 2^21473717761 is an apocalyptic number.

It is an amenable number.

21473717761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21473717761 is an equidigital number, since it uses as much as digits as its factorization.

21473717761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345744, while the sum is 46.

The spelling of 21473717761 in words is "twenty-one billion, four hundred seventy-three million, seven hundred seventeen thousand, seven hundred sixty-one".