66651540 has 24 divisors (see below), whose sum is σ = 186624480. Its totient is φ = 17773728.

The previous prime is 66651521. The next prime is 66651547. The reversal of 66651540 is 4515666.

66651540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66651547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 555370 + ... + 555489.

It is an arithmetic number, because the mean of its divisors is an integer number (7776020).

Almost surely, 2^66651540 is an apocalyptic number.

66651540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66651540 is an abundant number, since it is smaller than the sum of its proper divisors (119972940).

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

66651540 is a wasteful number, since it uses less digits than its factorization.

66651540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110871 (or 1110869 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 66651540 is about 8164.0394413550. The cubic root of 66651540 is about 405.4494629044.

The spelling of 66651540 in words is "sixty-six million, six hundred fifty-one thousand, five hundred forty".