636947640 has 384 divisors, whose sum is σ = 2547417600. Its totient is φ = 134784000.

The previous prime is 636947639. The next prime is 636947651. The reversal of 636947640 is 46749636.

636947640 is a `hidden beast` number, since 636 + 9 + 4 + 7 + 6 + 4 + 0 = 666.

It is a super-3 number, since 3×636947640³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2537515 + ... + 2537765.

It is an arithmetic number, because the mean of its divisors is an integer number (6633900).

Almost surely, 2^636947640 is an apocalyptic number.

636947640 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 636947640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1273708800).

636947640 is an abundant number, since it is smaller than the sum of its proper divisors (1910469960).

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

636947640 is a wasteful number, since it uses less digits than its factorization.

636947640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347 (or 340 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 45.

The square root of 636947640 is about 25237.8216175644. The cubic root of 636947640 is about 860.4016692278.

The spelling of 636947640 in words is "six hundred thirty-six million, nine hundred forty-seven thousand, six hundred forty".