66861989 has 4 divisors (see below), whose sum is σ = 69769056. Its totient is φ = 63954924.

The previous prime is 66861979. The next prime is 66862001. The reversal of 66861989 is 98916866.

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, and also an emirpimes, since its reverse is a distinct semiprime: 98916866 = 2 ⋅49458433.

It is a cyclic number.

It is not a de Polignac number, because 66861989 - 2⁴ = 66861973 is a prime.

It is a super-2 number, since 2×66861989² = 8941051146072242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 66861989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66861929) 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, 1453499 + ... + 1453544.

It is an arithmetic number, because the mean of its divisors is an integer number (17442264).

Almost surely, 2^66861989 is an apocalyptic number.

It is an amenable number.

66861989 is a deficient number, since it is larger than the sum of its proper divisors (2907067).

66861989 is a wasteful number, since it uses less digits than its factorization.

66861989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2907066.

The product of its digits is 1119744, while the sum is 53.

The square root of 66861989 is about 8176.9180624487. The cubic root of 66861989 is about 405.8757435601.

The spelling of 66861989 in words is "sixty-six million, eight hundred sixty-one thousand, nine hundred eighty-nine".