66618431 has 4 divisors (see below), whose sum is σ = 72674664. Its totient is φ = 60562200.

The previous prime is 66618421. The next prime is 66618457. The reversal of 66618431 is 13481666.

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 66618431 - 2⁶ = 66618367 is a prime.

It is a super-2 number, since 2×66618431² = 8876030697803522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66618391 and 66618400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66618401) 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, 3028100 + ... + 3028121.

It is an arithmetic number, because the mean of its divisors is an integer number (18168666).

Almost surely, 2^66618431 is an apocalyptic number.

66618431 is a deficient number, since it is larger than the sum of its proper divisors (6056233).

66618431 is a wasteful number, since it uses less digits than its factorization.

66618431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6056232.

The product of its digits is 20736, while the sum is 35.

The square root of 66618431 is about 8162.0114555176. The cubic root of 66618431 is about 405.3823164205.

The spelling of 66618431 in words is "sixty-six million, six hundred eighteen thousand, four hundred thirty-one".