66640025 has 6 divisors (see below), whose sum is σ = 82633662. Its totient is φ = 53312000.

The previous prime is 66640019. The next prime is 66640043. The reversal of 66640025 is 52004666.

It can be written as a sum of positive squares in 3 ways, for example, as 12411529 + 54228496 = 3523^2 + 7364^2 .

It is not a de Polignac number, because 66640025 - 2¹⁸ = 66377881 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 66640025.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1332776 + ... + 1332825.

It is an arithmetic number, because the mean of its divisors is an integer number (13772277).

Almost surely, 2^66640025 is an apocalyptic number.

It is an amenable number.

66640025 is a deficient number, since it is larger than the sum of its proper divisors (15993637).

66640025 is a wasteful number, since it uses less digits than its factorization.

66640025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2665611 (or 2665606 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 66640025 is about 8163.3341840206. The cubic root of 66640025 is about 405.4261125089.

The spelling of 66640025 in words is "sixty-six million, six hundred forty thousand, twenty-five".