66061639 has 4 divisors (see below), whose sum is σ = 75499024. Its totient is φ = 56624256.

The previous prime is 66061637. The next prime is 66061661. The reversal of 66061639 is 93616066.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93616066 = 2 ⋅46808033.

It is a cyclic number.

It is not a de Polignac number, because 66061639 - 2¹ = 66061637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66061598 and 66061607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66061637) 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, 4718682 + ... + 4718695.

It is an arithmetic number, because the mean of its divisors is an integer number (18874756).

Almost surely, 2^66061639 is an apocalyptic number.

66061639 is a deficient number, since it is larger than the sum of its proper divisors (9437385).

66061639 is an equidigital number, since it uses as much as digits as its factorization.

66061639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9437384.

The product of its (nonzero) digits is 34992, while the sum is 37.

The square root of 66061639 is about 8127.8311375176. The cubic root of 66061639 is about 404.2497699853.

The spelling of 66061639 in words is "sixty-six million, sixty-one thousand, six hundred thirty-nine".