66521223 has 16 divisors (see below), whose sum is σ = 103737600. Its totient is φ = 42013080.

The previous prime is 66521219. The next prime is 66521237. The reversal of 66521223 is 32212566.

66521223 is a `hidden beast` number, since 6 + 652 + 1 + 2 + 2 + 3 = 666.

It is not a de Polignac number, because 66521223 - 2² = 66521219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66521243) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 64323 + ... + 65348.

It is an arithmetic number, because the mean of its divisors is an integer number (6483600).

Almost surely, 2^66521223 is an apocalyptic number.

66521223 is a deficient number, since it is larger than the sum of its proper divisors (37216377).

66521223 is a wasteful number, since it uses less digits than its factorization.

66521223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129699 (or 129693 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

The square root of 66521223 is about 8156.0543769644. The cubic root of 66521223 is about 405.1850457546.

Adding to 66521223 its reverse (32212566), we get a palindrome (98733789).

It can be divided in two parts, 6652 and 1223, that added together give a triangular number (7875 = T₁₂₅).

The spelling of 66521223 in words is "sixty-six million, five hundred twenty-one thousand, two hundred twenty-three".