21161706210 has 24 divisors (see below), whose sum is σ = 55020436380. Its totient is φ = 5643121632.

The previous prime is 21161706193. The next prime is 21161706283. The reversal of 21161706210 is 1260716112.

It is a happy number.

21161706210 is a `hidden beast` number, since 21 + 1 + 6 + 17 + 0 + 621 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21099596049 + 62110161 = 145257^2 + 7881^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 117564945 + ... + 117565124.

Almost surely, 2^21161706210 is an apocalyptic number.

21161706210 is an abundant number, since it is smaller than the sum of its proper divisors (33858730170).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21161706210 is a wasteful number, since it uses less digits than its factorization.

21161706210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235130082 (or 235130079 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The spelling of 21161706210 in words is "twenty-one billion, one hundred sixty-one million, seven hundred six thousand, two hundred ten".