261709920 has 192 divisors, whose sum is σ = 948024000. Its totient is φ = 67350528.

The previous prime is 261709907. The next prime is 261709927. The reversal of 261709920 is 29907162.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261709927) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 124236 + ... + 126324.

It is an arithmetic number, because the mean of its divisors is an integer number (4937625).

Almost surely, 2^261709920 is an apocalyptic number.

261709920 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 261709920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (474012000).

261709920 is an abundant number, since it is smaller than the sum of its proper divisors (686314080).

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

261709920 is a wasteful number, since it uses less digits than its factorization.

261709920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2142 (or 2128 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 261709920 is about 16177.4509735001. The cubic root of 261709920 is about 639.6465496289.

The spelling of 261709920 in words is "two hundred sixty-one million, seven hundred nine thousand, nine hundred twenty".