66121445 has 16 divisors (see below), whose sum is σ = 85745520. Its totient is φ = 48658944.

The previous prime is 66121427. The next prime is 66121457. The reversal of 66121445 is 54412166.

It can be written as a sum of positive squares in 8 ways, for example, as 15626209 + 50495236 = 3953^2 + 7106^2 .

It is a cyclic number.

It is not a de Polignac number, because 66121445 - 2¹² = 66117349 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19001 + ... + 22209.

It is an arithmetic number, because the mean of its divisors is an integer number (5359095).

Almost surely, 2^66121445 is an apocalyptic number.

66121445 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66121445 is a deficient number, since it is larger than the sum of its proper divisors (19624075).

66121445 is a wasteful number, since it uses less digits than its factorization.

66121445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3544.

The product of its digits is 5760, while the sum is 29.

The square root of 66121445 is about 8131.5093924806. The cubic root of 66121445 is about 404.3717231089.

It can be divided in two parts, 66121 and 445, that added together give a palindrome (66566).

The spelling of 66121445 in words is "sixty-six million, one hundred twenty-one thousand, four hundred forty-five".