66428729 has 4 divisors (see below), whose sum is σ = 66491940. Its totient is φ = 66365520.

The previous prime is 66428711. The next prime is 66428767. The reversal of 66428729 is 92782466.

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 45589504 + 20839225 = 6752^2 + 4565^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66428729 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 66428729.

It is not an unprimeable number, because it can be changed into a prime (66428779) 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, 30002 + ... + 32139.

It is an arithmetic number, because the mean of its divisors is an integer number (16622985).

Almost surely, 2^66428729 is an apocalyptic number.

It is an amenable number.

66428729 is a deficient number, since it is larger than the sum of its proper divisors (63211).

66428729 is a wasteful number, since it uses less digits than its factorization.

66428729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63210.

The product of its digits is 290304, while the sum is 44.

The square root of 66428729 is about 8150.3821382804. The cubic root of 66428729 is about 404.9971630142.

The spelling of 66428729 in words is "sixty-six million, four hundred twenty-eight thousand, seven hundred twenty-nine".