61866809 has 4 divisors (see below), whose sum is σ = 63305616. Its totient is φ = 60428004.

The previous prime is 61866781. The next prime is 61866811. The reversal of 61866809 is 90866816.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61866809 is a prime.

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 61866809.

It is not an unprimeable number, because it can be changed into a prime (61866209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 719339 + ... + 719424.

It is an arithmetic number, because the mean of its divisors is an integer number (15826404).

Almost surely, 2^61866809 is an apocalyptic number.

It is an amenable number.

61866809 is a deficient number, since it is larger than the sum of its proper divisors (1438807).

61866809 is a wasteful number, since it uses less digits than its factorization.

61866809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438806.

The product of its (nonzero) digits is 124416, while the sum is 44.

The square root of 61866809 is about 7865.5456899061. The cubic root of 61866809 is about 395.5055408183.

The spelling of 61866809 in words is "sixty-one million, eight hundred sixty-six thousand, eight hundred nine".