66356421 has 4 divisors (see below), whose sum is σ = 88475232. Its totient is φ = 44237612.

The previous prime is 66356419. The next prime is 66356443. The reversal of 66356421 is 12465366.

66356421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 66356421 - 2¹ = 66356419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66356401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11059401 + ... + 11059406.

It is an arithmetic number, because the mean of its divisors is an integer number (22118808).

Almost surely, 2^66356421 is an apocalyptic number.

It is an amenable number.

66356421 is a deficient number, since it is larger than the sum of its proper divisors (22118811).

66356421 is a wasteful number, since it uses less digits than its factorization.

66356421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22118810.

The product of its digits is 25920, while the sum is 33.

The square root of 66356421 is about 8145.9450648774. The cubic root of 66356421 is about 404.8501625262.

The spelling of 66356421 in words is "sixty-six million, three hundred fifty-six thousand, four hundred twenty-one".