55666521 has 15 divisors (see below), whose sum is σ = 83256591. Its totient is φ = 37066248.

The previous prime is 55666519. The next prime is 55666531. The reversal of 55666521 is 12566655.

It is a happy number.

The square root of 55666521 is 7461.

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., 32046921 + 23619600 = 5661^2 + 4860^2 .

It is not a de Polignac number, because 55666521 - 2¹ = 55666519 is a prime.

It is not an unprimeable number, because it can be changed into a prime (55666511) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 66735 + ... + 67563.

Almost surely, 2^55666521 is an apocalyptic number.

55666521 is the 7461-st square number.

55666521 is the 3731-st centered octagonal number.

It is an amenable number.

55666521 is a deficient number, since it is larger than the sum of its proper divisors (27590070).

55666521 is an frugal number, since it uses more digits than its factorization.

55666521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670 (or 832 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The cubic root of 55666521 is about 381.8252926783.

Multiplying 55666521 by its sum of digits (36), we get a square (2003994756 = 44766²).

The spelling of 55666521 in words is "fifty-five million, six hundred sixty-six thousand, five hundred twenty-one".