261431089920 has 2160 divisors, whose sum is σ = 1271027714880. Its totient is φ = 49925652480.

The previous prime is 261431089903. The next prime is 261431089939. The reversal of 261431089920 is 29980134162.

261431089920 is a `hidden beast` number, since 2 + 614 + 3 + 1 + 0 + 8 + 9 + 9 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (2160).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 1141620366 + ... + 1141620594.

Almost surely, 2^261431089920 is an apocalyptic number.

261431089920 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 261431089920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (635513857440).

261431089920 is an abundant number, since it is smaller than the sum of its proper divisors (1009596624960).

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

261431089920 is a wasteful number, since it uses less digits than its factorization.

261431089920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 270 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 261431089920 in words is "two hundred sixty-one billion, four hundred thirty-one million, eighty-nine thousand, nine hundred twenty".