212656509 has 20 divisors (see below), whose sum is σ = 342110076. Its totient is φ = 130864896.

The previous prime is 212656489. The next prime is 212656523. The reversal of 212656509 is 905656212.

It can be written as a sum of positive squares in 2 ways, for example, as 82628100 + 130028409 = 9090^2 + 11403^2 .

It is not a de Polignac number, because 212656509 - 2⁸ = 212656253 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212656589) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 99924 + ... + 102029.

Almost surely, 2^212656509 is an apocalyptic number.

It is an amenable number.

212656509 is a deficient number, since it is larger than the sum of its proper divisors (129453567).

212656509 is a wasteful number, since it uses less digits than its factorization.

212656509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201978 (or 201969 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 212656509 is about 14582.7469634497. The cubic root of 212656509 is about 596.8880626473. Note that the first 3 decimals are identical.

The spelling of 212656509 in words is "two hundred twelve million, six hundred fifty-six thousand, five hundred nine".