1643261400 has 288 divisors, whose sum is σ = 6071598000. Its totient is φ = 394982400.

The previous prime is 1643261377. The next prime is 1643261419. The reversal of 1643261400 is 41623461.

1643261400 is a `hidden beast` number, since 1 + 6 + 43 + 2 + 614 + 0 + 0 = 666.

1643261400 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a zygodrome in base 5.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2949922 + ... + 2950478.

Almost surely, 2^1643261400 is an apocalyptic number.

1643261400 is a gapful number since it is divisible by the number (10) 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 1643261400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3035799000).

1643261400 is an abundant number, since it is smaller than the sum of its proper divisors (4428336600).

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

1643261400 is a wasteful number, since it uses less digits than its factorization.

1643261400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 739 (or 727 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 1643261400 is about 40537.1607293851. The cubic root of 1643261400 is about 1180.0549146138.

Adding to 1643261400 its reverse (41623461), we get a palindrome (1684884861).

The spelling of 1643261400 in words is "one billion, six hundred forty-three million, two hundred sixty-one thousand, four hundred".