66406973 has 4 divisors (see below), whose sum is σ = 66430620. Its totient is φ = 66383328.

The previous prime is 66406969. The next prime is 66406993. The reversal of 66406973 is 37960466.

It is a happy number.

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 60637369 + 5769604 = 7787^2 + 2402^2 .

It is a cyclic number.

It is not a de Polignac number, because 66406973 - 2² = 66406969 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66406973.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66406993) 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, 6938 + ... + 13451.

It is an arithmetic number, because the mean of its divisors is an integer number (16607655).

Almost surely, 2^66406973 is an apocalyptic number.

It is an amenable number.

66406973 is a deficient number, since it is larger than the sum of its proper divisors (23647).

66406973 is a wasteful number, since it uses less digits than its factorization.

66406973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23646.

The product of its (nonzero) digits is 163296, while the sum is 41.

The square root of 66406973 is about 8149.0473676375. The cubic root of 66406973 is about 404.9529447947.

The spelling of 66406973 in words is "sixty-six million, four hundred six thousand, nine hundred seventy-three".