66345521 has 4 divisors (see below), whose sum is σ = 72376944. Its totient is φ = 60314100.

The previous prime is 66345481. The next prime is 66345541. The reversal of 66345521 is 12554366.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66345521 - 2²² = 62151217 is a prime.

It is a super-2 number, since 2×66345521² = 8803456313522882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66345541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3015695 + ... + 3015716.

It is an arithmetic number, because the mean of its divisors is an integer number (18094236).

Almost surely, 2^66345521 is an apocalyptic number.

It is an amenable number.

66345521 is a deficient number, since it is larger than the sum of its proper divisors (6031423).

66345521 is a wasteful number, since it uses less digits than its factorization.

66345521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6031422.

The product of its digits is 21600, while the sum is 32.

The square root of 66345521 is about 8145.2759928685. The cubic root of 66345521 is about 404.8279938179.

Adding to 66345521 its reverse (12554366), we get a palindrome (78899887).

It can be divided in two parts, 66345 and 521, that added together give a palindrome (66866).

The spelling of 66345521 in words is "sixty-six million, three hundred forty-five thousand, five hundred twenty-one".