1643630478 has 64 divisors (see below), whose sum is σ = 3931410432. Its totient is φ = 448208640.

The previous prime is 1643630441. The next prime is 1643630489. The reversal of 1643630478 is 8740363461.

It is a happy number.

It is a super-2 number, since 2×1643630478² = 5403042296421016968, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86400 + ... + 103692.

It is an arithmetic number, because the mean of its divisors is an integer number (61428288).

Almost surely, 2^1643630478 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1643630478, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1965705216).

1643630478 is an abundant number, since it is smaller than the sum of its proper divisors (2287779954).

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

1643630478 is a wasteful number, since it uses less digits than its factorization.

1643630478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17409.

The product of its (nonzero) digits is 290304, while the sum is 42.

The square root of 1643630478 is about 40541.7128153215. The cubic root of 1643630478 is about 1180.1432551348.

The spelling of 1643630478 in words is "one billion, six hundred forty-three million, six hundred thirty thousand, four hundred seventy-eight".