261555400 has 96 divisors (see below), whose sum is σ = 629959680. Its totient is φ = 100928000.

The previous prime is 261555397. The next prime is 261555403. The reversal of 261555400 is 4555162.

It is an interprime number because it is at equal distance from previous prime (261555397) and next prime (261555403).

It is a super-2 number, since 2×261555400² = 136822454538320000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261555403) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 1369305 + ... + 1369495.

It is an arithmetic number, because the mean of its divisors is an integer number (6562080).

Almost surely, 2^261555400 is an apocalyptic number.

261555400 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 261555400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (314979840).

261555400 is an abundant number, since it is smaller than the sum of its proper divisors (368404280).

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

261555400 is a wasteful number, since it uses less digits than its factorization.

261555400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 28.

The square root of 261555400 is about 16172.6744850689. The cubic root of 261555400 is about 639.5206371385.

The spelling of 261555400 in words is "two hundred sixty-one million, five hundred fifty-five thousand, four hundred".