261428499072 has 192 divisors, whose sum is σ = 852796744800. Its totient is φ = 76205795328.

The previous prime is 261428499071. The next prime is 261428499131. The reversal of 261428499072 is 270994824162.

It is a happy number.

261428499072 is a `hidden beast` number, since 2 + 6 + 142 + 8 + 499 + 0 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×261428499072² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261428499071) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 174838 + ... + 743925.

Almost surely, 2^261428499072 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261428499072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (426398372400).

261428499072 is an abundant number, since it is smaller than the sum of its proper divisors (591368245728).

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

261428499072 is a wasteful number, since it uses less digits than its factorization.

261428499072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 918815 (or 918800 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 54.

The spelling of 261428499072 in words is "two hundred sixty-one billion, four hundred twenty-eight million, four hundred ninety-nine thousand, seventy-two".