261990288 has 100 divisors (see below), whose sum is σ = 866631040. Its totient is φ = 74851776.

The previous prime is 261990241. The next prime is 261990299. The reversal of 261990288 is 882099162.

261990288 is a `hidden beast` number, since 2 + 619 + 9 + 0 + 28 + 8 = 666.

It is a super-2 number, since 2×261990288² = 137277822012645888, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5368 + ... + 23511.

Almost surely, 2^261990288 is an apocalyptic number.

261990288 is a gapful number since it is divisible by the number (28) 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 261990288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (433315520).

261990288 is an abundant number, since it is smaller than the sum of its proper divisors (604640752).

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

261990288 is a wasteful number, since it uses less digits than its factorization.

261990288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28906 (or 28891 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 261990288 is about 16186.1140487765. The cubic root of 261990288 is about 639.8748843965.

The spelling of 261990288 in words is "two hundred sixty-one million, nine hundred ninety thousand, two hundred eighty-eight".