66520387 has 12 divisors (see below), whose sum is σ = 70926960. Its totient is φ = 62372592.

The previous prime is 66520381. The next prime is 66520417. The reversal of 66520387 is 78302566.

It is not a de Polignac number, because 66520387 - 2²³ = 58131779 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66520381) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36289 + ... + 38077.

It is an arithmetic number, because the mean of its divisors is an integer number (5910580).

Almost surely, 2^66520387 is an apocalyptic number.

66520387 is a deficient number, since it is larger than the sum of its proper divisors (4406573).

66520387 is a wasteful number, since it uses less digits than its factorization.

66520387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1930 (or 1911 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 66520387 is about 8156.0031265320. The cubic root of 66520387 is about 405.1833483710.

It can be divided in two parts, 665203 and 87, that multiplied together give a triangular number (57872661 = T₁₀₇₅₈).

The spelling of 66520387 in words is "sixty-six million, five hundred twenty thousand, three hundred eighty-seven".