655810638 has 64 divisors (see below), whose sum is σ = 1568996352. Its totient is φ = 178675200.

The previous prime is 655810633. The next prime is 655810657. The reversal of 655810638 is 836018556.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 655810638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655810633) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 386520 + ... + 388212.

It is an arithmetic number, because the mean of its divisors is an integer number (24515568).

Almost surely, 2^655810638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 655810638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (784498176).

655810638 is an abundant number, since it is smaller than the sum of its proper divisors (913185714).

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

655810638 is a wasteful number, since it uses less digits than its factorization.

655810638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2129.

The product of its (nonzero) digits is 172800, while the sum is 42.

The square root of 655810638 is about 25608.8000109337. The cubic root of 655810638 is about 868.8126834470.

The spelling of 655810638 in words is "six hundred fifty-five million, eight hundred ten thousand, six hundred thirty-eight".