66251440 has 40 divisors (see below), whose sum is σ = 154432080. Its totient is φ = 26432256.

The previous prime is 66251413. The next prime is 66251441. The reversal of 66251440 is 4415266.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 66251399 and 66251408.

It is not an unprimeable number, because it can be changed into a prime (66251441) 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, 39907 + ... + 41533.

It is an arithmetic number, because the mean of its divisors is an integer number (3860802).

Almost surely, 2^66251440 is an apocalyptic number.

It is an amenable number.

66251440 is an abundant number, since it is smaller than the sum of its proper divisors (88180640).

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

66251440 is a wasteful number, since it uses less digits than its factorization.

66251440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2149 (or 2143 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 66251440 is about 8139.4987560660. The cubic root of 66251440 is about 404.6365483922.

The spelling of 66251440 in words is "sixty-six million, two hundred fifty-one thousand, four hundred forty".