66913509 has 16 divisors (see below), whose sum is σ = 100259712. Its totient is φ = 39386688.

The previous prime is 66913489. The next prime is 66913519. The reversal of 66913509 is 90531966.

It is not a de Polignac number, because 66913509 - 2⁷ = 66913381 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66913519) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36402 + ... + 38195.

It is an arithmetic number, because the mean of its divisors is an integer number (6266232).

Almost surely, 2^66913509 is an apocalyptic number.

66913509 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

It is an amenable number.

66913509 is a deficient number, since it is larger than the sum of its proper divisors (33346203).

66913509 is a wasteful number, since it uses less digits than its factorization.

66913509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74636.

The product of its (nonzero) digits is 43740, while the sum is 39.

The square root of 66913509 is about 8180.0677870052. The cubic root of 66913509 is about 405.9799649573.

The spelling of 66913509 in words is "sixty-six million, nine hundred thirteen thousand, five hundred nine".