261217920 has 256 divisors, whose sum is σ = 904193280. Its totient is φ = 63897600.

The previous prime is 261217907. The next prime is 261217927. The reversal of 261217920 is 29712162.

261217920 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261217927) 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, 1729845 + ... + 1729995.

It is an arithmetic number, because the mean of its divisors is an integer number (3532005).

Almost surely, 2^261217920 is an apocalyptic number.

261217920 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 261217920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (452096640).

261217920 is an abundant number, since it is smaller than the sum of its proper divisors (642975360).

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

261217920 is a wasteful number, since it uses less digits than its factorization.

261217920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 231 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 261217920 is about 16162.2374688655. The cubic root of 261217920 is about 639.2454649488.

The spelling of 261217920 in words is "two hundred sixty-one million, two hundred seventeen thousand, nine hundred twenty".