66612391 has 4 divisors (see below), whose sum is σ = 68909400. Its totient is φ = 64315384.

The previous prime is 66612373. The next prime is 66612419. The reversal of 66612391 is 19321666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66612391 - 2¹¹ = 66610343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66612191) 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, 1148461 + ... + 1148518.

It is an arithmetic number, because the mean of its divisors is an integer number (17227350).

Almost surely, 2^66612391 is an apocalyptic number.

66612391 is a deficient number, since it is larger than the sum of its proper divisors (2297009).

66612391 is a wasteful number, since it uses less digits than its factorization.

66612391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2297008.

The product of its digits is 11664, while the sum is 34.

The square root of 66612391 is about 8161.6414402986. The cubic root of 66612391 is about 405.3700646399.

The spelling of 66612391 in words is "sixty-six million, six hundred twelve thousand, three hundred ninety-one".