261209491200 has 1728 divisors, whose sum is σ = 1175224780800. Its totient is φ = 55472947200.

The previous prime is 261209491199. The next prime is 261209491217. The reversal of 261209491200 is 2194902162.

261209491200 is a `hidden beast` number, since 26 + 120 + 9 + 491 + 20 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1728).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1140652686 + ... + 1140652914.

Almost surely, 2^261209491200 is an apocalyptic number.

261209491200 is a gapful number since it is divisible by the number (20) 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 261209491200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (587612390400).

261209491200 is an abundant number, since it is smaller than the sum of its proper divisors (914015289600).

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

261209491200 is a wasteful number, since it uses less digits than its factorization.

261209491200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 261209491200 in words is "two hundred sixty-one billion, two hundred nine million, four hundred ninety-one thousand, two hundred".