660551891400 has 72 divisors (see below), whose sum is σ = 2218353441330. Its totient is φ = 176147170560.

The previous prime is 660551891393. The next prime is 660551891407. The reversal of 660551891400 is 4198155066.

660551891400 is a `hidden beast` number, since 6 + 6 + 0 + 5 + 518 + 91 + 40 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (660551891393) and next prime (660551891407).

It can be written as a sum of positive squares in 3 ways, for example, as 518080369284 + 142471522116 = 719778^2 + 377454^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (660551891407) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 183484837 + ... + 183488436.

Almost surely, 2^660551891400 is an apocalyptic number.

660551891400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

660551891400 is an abundant number, since it is smaller than the sum of its proper divisors (1557801549930).

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

660551891400 is a wasteful number, since it uses less digits than its factorization.

660551891400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366973295 (or 366973283 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The spelling of 660551891400 in words is "six hundred sixty billion, five hundred fifty-one million, eight hundred ninety-one thousand, four hundred".