261961920 has 168 divisors, whose sum is σ = 983071440. Its totient is φ = 63498240.

The previous prime is 261961919. The next prime is 261961933. The reversal of 261961920 is 29169162.

261961920 is a `hidden beast` number, since 2 + 6 + 19 + 619 + 20 = 666.

261961920 is digitally balanced in base 2, because in such base 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 (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27546 + ... + 35814.

Almost surely, 2^261961920 is an apocalyptic number.

261961920 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 261961920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (491535720).

261961920 is an abundant number, since it is smaller than the sum of its proper divisors (721109520).

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

261961920 is a wasteful number, since it uses less digits than its factorization.

261961920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8303 (or 8290 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 261961920 is about 16185.2377183655. The cubic root of 261961920 is about 639.8517885965.

The spelling of 261961920 in words is "two hundred sixty-one million, nine hundred sixty-one thousand, nine hundred twenty".