66891600 has 180 divisors, whose sum is σ = 246012156. Its totient is φ = 16773120.

The previous prime is 66891589. The next prime is 66891637. The reversal of 66891600 is 619866.

It can be written as a sum of positive squares in 6 ways, for example, as 7354944 + 59536656 = 2712^2 + 7716^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 60654 + ... + 61746.

Almost surely, 2^66891600 is an apocalyptic number.

66891600 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66891600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123006078).

66891600 is an abundant number, since it is smaller than the sum of its proper divisors (179120556).

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

66891600 is a wasteful number, since it uses less digits than its factorization.

66891600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1134 (or 1120 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 66891600 is about 8178.7285075371. The cubic root of 66891600 is about 405.9356511053.

The spelling of 66891600 in words is "sixty-six million, eight hundred ninety-one thousand, six hundred".