66561365 has 8 divisors (see below), whose sum is σ = 86017848. Its totient is φ = 49152960.

The previous prime is 66561359. The next prime is 66561373. The reversal of 66561365 is 56316566.

It can be written as a sum of positive squares in 4 ways, for example, as 643204 + 65918161 = 802^2 + 8119^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66561365 - 2⁴ = 66561349 is a prime.

It is a Duffinian number.

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 7 ways as a sum of consecutive naturals, for example, 511946 + ... + 512075.

It is an arithmetic number, because the mean of its divisors is an integer number (10752231).

Almost surely, 2^66561365 is an apocalyptic number.

66561365 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66561365 is a deficient number, since it is larger than the sum of its proper divisors (19456483).

66561365 is a wasteful number, since it uses less digits than its factorization.

66561365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1024039.

The product of its digits is 97200, while the sum is 38.

The square root of 66561365 is about 8158.5148771085. The cubic root of 66561365 is about 405.2665318669.

The spelling of 66561365 in words is "sixty-six million, five hundred sixty-one thousand, three hundred sixty-five".