66221805 has 48 divisors (see below), whose sum is σ = 116159616. Its totient is φ = 32198400.

The previous prime is 66221789. The next prime is 66221861. The reversal of 66221805 is 50812266.

It is not a de Polignac number, because 66221805 - 2⁴ = 66221789 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 382699 + ... + 382871.

It is an arithmetic number, because the mean of its divisors is an integer number (2419992).

Almost surely, 2^66221805 is an apocalyptic number.

66221805 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66221805 is a deficient number, since it is larger than the sum of its proper divisors (49937811).

66221805 is a wasteful number, since it uses less digits than its factorization.

66221805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358 (or 345 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 66221805 is about 8137.6781086499. The cubic root of 66221805 is about 404.5762065967.

The spelling of 66221805 in words is "sixty-six million, two hundred twenty-one thousand, eight hundred five".