66501640 has 32 divisors (see below), whose sum is σ = 154791000. Its totient is φ = 25682944.

The previous prime is 66501629. The next prime is 66501649. The reversal of 66501640 is 4610566.

It can be written as a sum of positive squares in 4 ways, for example, as 35832196 + 30669444 = 5986^2 + 5538^2 .

It is a junction number, because it is equal to n+sod(n) for n = 66501599 and 66501608.

It is not an unprimeable number, because it can be changed into a prime (66501649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27505 + ... + 29824.

Almost surely, 2^66501640 is an apocalyptic number.

It is an amenable number.

66501640 is an abundant number, since it is smaller than the sum of its proper divisors (88289360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66501640 is a wasteful number, since it uses less digits than its factorization.

66501640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57369 (or 57365 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 66501640 is about 8154.8537693818. The cubic root of 66501640 is about 405.1452814150.

The spelling of 66501640 in words is "sixty-six million, five hundred one thousand, six hundred forty".