217031129956 has 27 divisors (see below), whose sum is σ = 383500346859. Its totient is φ = 107469695808.

The previous prime is 217031129951. The next prime is 217031129977. The reversal of 217031129956 is 659921130712.

The square root of 217031129956 is 465866.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 28140062500 + 188891067456 = 167750^2 + 434616^2 .

It is a super-2 number, since 2×217031129956² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217031129951) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 101557720 + ... + 101559856.

Almost surely, 2^217031129956 is an apocalyptic number.

217031129956 is the 465866-th square number.

It is an amenable number.

217031129956 is a deficient number, since it is larger than the sum of its proper divisors (166469216903).

217031129956 is an frugal number, since it uses more digits than its factorization.

217031129956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4496 (or 2248 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 46.

The spelling of 217031129956 in words is "two hundred seventeen billion, thirty-one million, one hundred twenty-nine thousand, nine hundred fifty-six".