666642493440 has 2080 divisors, whose sum is σ = 3164958365184. Its totient is φ = 129950023680.

The previous prime is 666642493421. The next prime is 666642493459. The reversal of 666642493440 is 44394246666.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (666642493421) and next prime (666642493459).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 2171473767 + ... + 2171474073.

Almost surely, 2^666642493440 is an apocalyptic number.

666642493440 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 666642493440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1582479182592).

666642493440 is an abundant number, since it is smaller than the sum of its proper divisors (2498315871744).

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

666642493440 is a wasteful number, since it uses less digits than its factorization.

666642493440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 383 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 17915904, while the sum is 54.

The spelling of 666642493440 in words is "six hundred sixty-six billion, six hundred forty-two million, four hundred ninety-three thousand, four hundred forty".