65566443421 has 4 divisors (see below), whose sum is σ = 69423293052. Its totient is φ = 61709593792.

The previous prime is 65566443419. The next prime is 65566443431. The reversal of 65566443421 is 12434466556.

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 55644092100 + 9922351321 = 235890^2 + 99611^2 .

It is a cyclic number.

It is not a de Polignac number, because 65566443421 - 2¹ = 65566443419 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 (65566443431) 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, 1928424790 + ... + 1928424823.

It is an arithmetic number, because the mean of its divisors is an integer number (17355823263).

Almost surely, 2^65566443421 is an apocalyptic number.

It is an amenable number.

65566443421 is a deficient number, since it is larger than the sum of its proper divisors (3856849631).

65566443421 is a wasteful number, since it uses less digits than its factorization.

65566443421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3856849630.

The product of its digits is 2073600, while the sum is 46.

The spelling of 65566443421 in words is "sixty-five billion, five hundred sixty-six million, four hundred forty-three thousand, four hundred twenty-one".