261544465642572 has 192 divisors, whose sum is σ = 782793817128960. Its totient is φ = 73970890797888.

The previous prime is 261544465642571. The next prime is 261544465642573. The reversal of 261544465642572 is 275246564445162.

261544465642572 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 4 + 4 + 4 + 6 + 56 + 4 + 2 + 572 = 666.

It is an interprime number because it is at equal distance from previous prime (261544465642571) and next prime (261544465642573).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (261544465642571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 187981053 + ... + 189367275.

It is an arithmetic number, because the mean of its divisors is an integer number (4077051130880).

Almost surely, 2^{261544465642572} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261544465642572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (391396908564480).

261544465642572 is an abundant number, since it is smaller than the sum of its proper divisors (521249351486388).

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

261544465642572 is a wasteful number, since it uses less digits than its factorization.

261544465642572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1388769 (or 1388761 counting only the distinct ones).

The product of its digits is 387072000, while the sum is 63.

The spelling of 261544465642572 in words is "two hundred sixty-one trillion, five hundred forty-four billion, four hundred sixty-five million, six hundred forty-two thousand, five hundred seventy-two".