66515601 has 4 divisors (see below), whose sum is σ = 88687472. Its totient is φ = 44343732.

The previous prime is 66515567. The next prime is 66515623. The reversal of 66515601 is 10651566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66515601 - 2⁹ = 66515089 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66515641) 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, 11085931 + ... + 11085936.

It is an arithmetic number, because the mean of its divisors is an integer number (22171868).

Almost surely, 2^66515601 is an apocalyptic number.

It is an amenable number.

66515601 is a deficient number, since it is larger than the sum of its proper divisors (22171871).

66515601 is a wasteful number, since it uses less digits than its factorization.

66515601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22171870.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 66515601 is about 8155.7097177376. The cubic root of 66515601 is about 405.1736307786.

The spelling of 66515601 in words is "sixty-six million, five hundred fifteen thousand, six hundred one".