261809040 has 80 divisors (see below), whose sum is σ = 833571648. Its totient is φ = 67926528.

The previous prime is 261809039. The next prime is 261809057. The reversal of 261809040 is 40908162.

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 = 261808989 and 261809007.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5862 + ... + 23621.

Almost surely, 2^261809040 is an apocalyptic number.

261809040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261809040 is an abundant number, since it is smaller than the sum of its proper divisors (571762608).

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

261809040 is a wasteful number, since it uses less digits than its factorization.

261809040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29536 (or 29530 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 261809040 is about 16180.5142069095. The cubic root of 261809040 is about 639.7272926687.

The spelling of 261809040 in words is "two hundred sixty-one million, eight hundred nine thousand, forty".