261673251840 has 2816 divisors, whose sum is σ = 1309996154880. Its totient is φ = 47775744000.

The previous prime is 261673251821. The next prime is 261673251869. The reversal of 261673251840 is 48152376162.

261673251840 is a `hidden beast` number, since 2 + 6 + 1 + 67 + 32 + 518 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (2816).

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 255 ways as a sum of consecutive naturals, for example, 4289725410 + ... + 4289725470.

Almost surely, 2^261673251840 is an apocalyptic number.

261673251840 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 261673251840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (654998077440).

261673251840 is an abundant number, since it is smaller than the sum of its proper divisors (1048322903040).

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

261673251840 is a wasteful number, since it uses less digits than its factorization.

261673251840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 261673251840 in words is "two hundred sixty-one billion, six hundred seventy-three million, two hundred fifty-one thousand, eight hundred forty".