261286920 has 96 divisors (see below), whose sum is σ = 868982400. Its totient is φ = 68052096.

The previous prime is 261286913. The next prime is 261286937. The reversal of 261286920 is 29682162.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

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, 7041 + ... + 23919.

It is an arithmetic number, because the mean of its divisors is an integer number (9051900).

Almost surely, 2^261286920 is an apocalyptic number.

261286920 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 261286920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (434491200).

261286920 is an abundant number, since it is smaller than the sum of its proper divisors (607695480).

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

261286920 is a wasteful number, since it uses less digits than its factorization.

261286920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16939 (or 16932 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 261286920 is about 16164.3719333601. The cubic root of 261286920 is about 639.3017449748.

The spelling of 261286920 in words is "two hundred sixty-one million, two hundred eighty-six thousand, nine hundred twenty".