645740550 has 216 divisors, whose sum is σ = 2148750864. Its totient is φ = 136131840.

The previous prime is 645740507. The next prime is 645740551. The reversal of 645740550 is 55047546.

It is a happy number.

645740550 is a `hidden beast` number, since 64 + 5 + 7 + 40 + 550 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645740551) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 531744 + ... + 532956.

Almost surely, 2^645740550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645740550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1074375432).

645740550 is an abundant number, since it is smaller than the sum of its proper divisors (1503010314).

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

645740550 is a wasteful number, since it uses less digits than its factorization.

645740550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1264 (or 1243 counting only the distinct ones).

The product of its (nonzero) digits is 84000, while the sum is 36.

The square root of 645740550 is about 25411.4255798450. The cubic root of 645740550 is about 864.3428021785.

The spelling of 645740550 in words is "six hundred forty-five million, seven hundred forty thousand, five hundred fifty".