1261638000 has 960 divisors, whose sum is σ = 5793914880. Its totient is φ = 248832000.

The previous prime is 1261637989. The next prime is 1261638043. The reversal of 1261638000 is 8361621.

1261638000 is a `hidden beast` number, since 1 + 26 + 1 + 638 + 0 + 0 + 0 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 40697985 + ... + 40698015.

It is an arithmetic number, because the mean of its divisors is an integer number (6035328).

Almost surely, 2^1261638000 is an apocalyptic number.

1261638000 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 1261638000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2896957440).

1261638000 is an abundant number, since it is smaller than the sum of its proper divisors (4532276880).

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

1261638000 is a wasteful number, since it uses less digits than its factorization.

1261638000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 1261638000 is about 35519.5439159908. The cubic root of 1261638000 is about 1080.5501312488.

Adding to 1261638000 its reverse (8361621), we get a palindrome (1269999621).

The spelling of 1261638000 in words is "one billion, two hundred sixty-one million, six hundred thirty-eight thousand".