261137920 has 80 divisors (see below), whose sum is σ = 634178160. Its totient is φ = 103112704.

The previous prime is 261137917. The next prime is 261137923. The reversal of 261137920 is 29731162.

It is an interprime number because it is at equal distance from previous prime (261137917) and next prime (261137923).

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261137923) 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, 211866 + ... + 213094.

It is an arithmetic number, because the mean of its divisors is an integer number (7927227).

Almost surely, 2^261137920 is an apocalyptic number.

261137920 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 261137920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (317089080).

261137920 is an abundant number, since it is smaller than the sum of its proper divisors (373040240).

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

261137920 is an equidigital number, since it uses as much as digits as its factorization.

261137920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1335 (or 1319 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 261137920 is about 16159.7623744905. The cubic root of 261137920 is about 639.1802003367.

The spelling of 261137920 in words is "two hundred sixty-one million, one hundred thirty-seven thousand, nine hundred twenty".