1211666481 has 27 divisors (see below), whose sum is σ = 1800274827. Its totient is φ = 785291040.

The previous prime is 1211666471. The next prime is 1211666501. The reversal of 1211666481 is 1846661121.

The square root of 1211666481 is 34809.

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

It can be written as a sum of positive squares in only one way, i.e., 58384881 + 1153281600 = 7641^2 + 33960^2 .

It is not a de Polignac number, because 1211666481 - 2¹⁵ = 1211633713 is a prime.

It is a super-4 number, since 4×1211666481⁴ (a number of 37 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (1211666441) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4281366 + ... + 4281648.

Almost surely, 2^1211666481 is an apocalyptic number.

1211666481 is the 34809-th square number.

1211666481 is the 17405-th centered octagonal number.

It is an amenable number.

1211666481 is a deficient number, since it is larger than the sum of its proper divisors (588608346).

1211666481 is an frugal number, since it uses more digits than its factorization.

1211666481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654 (or 327 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The cubic root of 1211666481 is about 1066.0912150744.

Multiplying 1211666481 by its sum of digits (36), we get a square (43619993316 = 208854²).

The spelling of 1211666481 in words is "one billion, two hundred eleven million, six hundred sixty-six thousand, four hundred eighty-one".