2166064681 has 9 divisors (see below), whose sum is σ = 2381443869. Its totient is φ = 1968684300.

The previous prime is 2166064651. The next prime is 2166064709. The reversal of 2166064681 is 1864606612.

It is a happy number.

The square root of 2166064681 is 46541.

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

It is not a de Polignac number, because 2166064681 - 2⁷ = 2166064553 is a prime.

It is a super-2 number, since 2×2166064681² = 9383672404551263522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2166064651) 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, 509836 + ... + 514066.

Almost surely, 2^2166064681 is an apocalyptic number.

2166064681 is the 46541-st square number.

2166064681 is the 23271-st centered octagonal number.

It is an amenable number.

2166064681 is a deficient number, since it is larger than the sum of its proper divisors (215379188).

2166064681 is an frugal number, since it uses more digits than its factorization.

2166064681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8484 (or 4242 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 40.

The cubic root of 2166064681 is about 1293.8694945413.

Multiplying 2166064681 by its product of nonzero digits (82944), we get a square (179662068900864 = 13403808²).

The spelling of 2166064681 in words is "two billion, one hundred sixty-six million, sixty-four thousand, six hundred eighty-one".