261221454450 has 144 divisors (see below), whose sum is σ = 768796677792. Its totient is φ = 63063360000.

The previous prime is 261221454427. The next prime is 261221454479. The reversal of 261221454450 is 54454122162.

261221454450 is a `hidden beast` number, since 2 + 61 + 2 + 2 + 1 + 4 + 544 + 50 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1083465 + ... + 1302435.

It is an arithmetic number, because the mean of its divisors is an integer number (5338865818).

Almost surely, 2^261221454450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261221454450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (384398338896).

261221454450 is an abundant number, since it is smaller than the sum of its proper divisors (507575223342).

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

261221454450 is a wasteful number, since it uses less digits than its factorization.

261221454450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219241 (or 219233 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 36.

The spelling of 261221454450 in words is "two hundred sixty-one billion, two hundred twenty-one million, four hundred fifty-four thousand, four hundred fifty".