66620831 has 4 divisors (see below), whose sum is σ = 68421432. Its totient is φ = 64820232.

The previous prime is 66620759. The next prime is 66620833. The reversal of 66620831 is 13802666.

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 66620831 - 2¹⁸ = 66358687 is a prime.

It is a super-2 number, since 2×66620831² = 8876670246261122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66620833) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 900245 + ... + 900318.

It is an arithmetic number, because the mean of its divisors is an integer number (17105358).

Almost surely, 2^66620831 is an apocalyptic number.

66620831 is a deficient number, since it is larger than the sum of its proper divisors (1800601).

66620831 is a wasteful number, since it uses less digits than its factorization.

66620831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800600.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 66620831 is about 8162.1584767756. The cubic root of 66620831 is about 405.3871844721.

The spelling of 66620831 in words is "sixty-six million, six hundred twenty thousand, eight hundred thirty-one".