261537984 has 168 divisors, whose sum is σ = 792163008. Its totient is φ = 85536000.

The previous prime is 261537977. The next prime is 261538007. The reversal of 261537984 is 489735162.

261537984 is a `hidden beast` number, since 26 + 1 + 537 + 98 + 4 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1041859 + ... + 1042109.

It is an arithmetic number, because the mean of its divisors is an integer number (4715256).

Almost surely, 2^261537984 is an apocalyptic number.

261537984 is a gapful number since it is divisible by the number (24) 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 261537984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (396081504).

261537984 is an abundant number, since it is smaller than the sum of its proper divisors (530625024).

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

261537984 is an equidigital number, since it uses as much as digits as its factorization.

261537984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 323 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 261537984 is about 16172.1360370237. The cubic root of 261537984 is about 639.5064423909.

The spelling of 261537984 in words is "two hundred sixty-one million, five hundred thirty-seven thousand, nine hundred eighty-four".