261225840 has 80 divisors (see below), whose sum is σ = 835946496. Its totient is φ = 67411200.

The previous prime is 261225821. The next prime is 261225847. The reversal of 261225840 is 48522162.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 261225798 and 261225807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261225847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10116 + ... + 24995.

Almost surely, 2^261225840 is an apocalyptic number.

261225840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261225840 is an abundant number, since it is smaller than the sum of its proper divisors (574720656).

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

261225840 is a wasteful number, since it uses less digits than its factorization.

261225840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35158 (or 35152 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

The square root of 261225840 is about 16162.4824825891. The cubic root of 261225840 is about 639.2519254205.

The spelling of 261225840 in words is "two hundred sixty-one million, two hundred twenty-five thousand, eight hundred forty".