261717240 has 64 divisors (see below), whose sum is σ = 786736800. Its totient is φ = 69650432.

The previous prime is 261717217. The next prime is 261717241. The reversal of 261717240 is 42717162.

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 = 261717198 and 261717207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261717241) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66364 + ... + 70196.

Almost surely, 2^261717240 is an apocalyptic number.

261717240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261717240 is an abundant number, since it is smaller than the sum of its proper divisors (525019560).

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

261717240 is a wasteful number, since it uses less digits than its factorization.

261717240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4416 (or 4412 counting only the distinct ones).

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 261717240 is about 16177.6772127521. The cubic root of 261717240 is about 639.6525131897.

It can be divided in two parts, 26171 and 7240, that added together give a triangular number (33411 = T₂₅₈).

The spelling of 261717240 in words is "two hundred sixty-one million, seven hundred seventeen thousand, two hundred forty".