2166557317929 has 45 divisors (see below), whose sum is σ = 3286835059431. Its totient is φ = 1422230879520.

The previous prime is 2166557317927. The next prime is 2166557317961. The reversal of 2166557317929 is 9297137556612.

The square root of 2166557317929 is 1471923.

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

2166557317929 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 557 + 3 + 1 + 79 + 2 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 209468236329 + 1957089081600 = 457677^2 + 1398960^2 .

It is not a de Polignac number, because 2166557317929 - 2¹ = 2166557317927 is a prime.

It is a super-2 number, since 2×2166557317929² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2166557317927) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 887568349 + ... + 887570789.

Almost surely, 2^{2166557317929} is an apocalyptic number.

2166557317929 is the 1471923-rd square number.

2166557317929 is the 735962-nd centered octagonal number.

It is an amenable number.

2166557317929 is a deficient number, since it is larger than the sum of its proper divisors (1120277741502).

2166557317929 is an frugal number, since it uses more digits than its factorization.

2166557317929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5028 (or 2511 counting only the distinct ones).

The product of its digits is 42865200, while the sum is 63.

The spelling of 2166557317929 in words is "two trillion, one hundred sixty-six billion, five hundred fifty-seven million, three hundred seventeen thousand, nine hundred twenty-nine".