261681720 has 32 divisors (see below), whose sum is σ = 785045520. Its totient is φ = 69781760.

The previous prime is 261681701. The next prime is 261681727. The reversal of 261681720 is 27186162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261681727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1090221 + ... + 1090460.

Almost surely, 2^261681720 is an apocalyptic number.

261681720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261681720 is an abundant number, since it is smaller than the sum of its proper divisors (523363800).

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

261681720 is a wasteful number, since it uses less digits than its factorization.

261681720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2180695 (or 2180691 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 261681720 is about 16176.5793664792. The cubic root of 261681720 is about 639.6235742157.

The spelling of 261681720 in words is "two hundred sixty-one million, six hundred eighty-one thousand, seven hundred twenty".