66220421 has 4 divisors (see below), whose sum is σ = 66603372. Its totient is φ = 65837472.

The previous prime is 66220403. The next prime is 66220459. The reversal of 66220421 is 12402266.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40322500 + 25897921 = 6350^2 + 5089^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66220421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66280421) 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, 191216 + ... + 191561.

It is an arithmetic number, because the mean of its divisors is an integer number (16650843).

Almost surely, 2^66220421 is an apocalyptic number.

It is an amenable number.

66220421 is a deficient number, since it is larger than the sum of its proper divisors (382951).

66220421 is a wasteful number, since it uses less digits than its factorization.

66220421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382950.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 66220421 is about 8137.5930716644. The cubic root of 66220421 is about 404.5733881023.

Adding to 66220421 its reverse (12402266), we get a palindrome (78622687).

The spelling of 66220421 in words is "sixty-six million, two hundred twenty thousand, four hundred twenty-one".