666544536 has 96 divisors (see below), whose sum is σ = 2102124960. Its totient is φ = 186840576.

The previous prime is 666544519. The next prime is 666544537. The reversal of 666544536 is 635445666.

It is a junction number, because it is equal to n+sod(n) for n = 666544491 and 666544500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666544537) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14236 + ... + 39188.

It is an arithmetic number, because the mean of its divisors is an integer number (21897135).

Almost surely, 2^666544536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666544536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1051062480).

666544536 is an abundant number, since it is smaller than the sum of its proper divisors (1435580424).

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

666544536 is a wasteful number, since it uses less digits than its factorization.

666544536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25025 (or 25018 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 45.

The square root of 666544536 is about 25817.5238161990. The cubic root of 666544536 is about 873.5271159961.

It can be divided in two parts, 66654 and 4536, that multiplied together give a square (302342544 = 17388²).

The spelling of 666544536 in words is "six hundred sixty-six million, five hundred forty-four thousand, five hundred thirty-six".