21670705557 has 6 divisors (see below), whose sum is σ = 31302130262. Its totient is φ = 14447137032.

The previous prime is 21670705543. The next prime is 21670705633. The reversal of 21670705557 is 75550707612.

It is a happy number.

21670705557 is a `hidden beast` number, since 21 + 6 + 7 + 0 + 70 + 5 + 557 = 666.

It can be written as a sum of positive squares in only one way, i.e., 17775822276 + 3894883281 = 133326^2 + 62409^2 .

It is not a de Polignac number, because 21670705557 - 2¹⁰ = 21670704533 is a prime.

It is a super-3 number, since 3×21670705557³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21670705757) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1203928078 + ... + 1203928095.

Almost surely, 2^21670705557 is an apocalyptic number.

It is an amenable number.

21670705557 is a deficient number, since it is larger than the sum of its proper divisors (9631424705).

21670705557 is a wasteful number, since it uses less digits than its factorization.

21670705557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2407856179 (or 2407856176 counting only the distinct ones).

The product of its (nonzero) digits is 514500, while the sum is 45.

The spelling of 21670705557 in words is "twenty-one billion, six hundred seventy million, seven hundred five thousand, five hundred fifty-seven".