261437220 has 240 divisors, whose sum is σ = 948423168. Its totient is φ = 59581440.

The previous prime is 261437219. The next prime is 261437243. The reversal of 261437220 is 22734162.

261437220 is a `hidden beast` number, since 2 + 6 + 1 + 437 + 220 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 302509 + ... + 303371.

Almost surely, 2^261437220 is an apocalyptic number.

261437220 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 261437220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (474211584).

261437220 is an abundant number, since it is smaller than the sum of its proper divisors (686985948).

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

261437220 is a wasteful number, since it uses less digits than its factorization.

261437220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 912 (or 901 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 261437220 is about 16169.0203784892. The cubic root of 261437220 is about 639.4243032645.

The spelling of 261437220 in words is "two hundred sixty-one million, four hundred thirty-seven thousand, two hundred twenty".