261364221456 has 320 divisors, whose sum is σ = 780223062528. Its totient is φ = 74681155584.

The previous prime is 261364221451. The next prime is 261364221491. The reversal of 261364221456 is 654122463162.

It is a happy number.

It is a super-2 number, since 2×261364221456² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261364221451) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 403962925 + ... + 403963571.

Almost surely, 2^261364221456 is an apocalyptic number.

261364221456 is a gapful number since it is divisible by the number (26) 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 261364221456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (390111531264).

261364221456 is an abundant number, since it is smaller than the sum of its proper divisors (518858841072).

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

261364221456 is a wasteful number, since it uses less digits than its factorization.

261364221456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1138 (or 1132 counting only the distinct ones).

The product of its digits is 414720, while the sum is 42.

The spelling of 261364221456 in words is "two hundred sixty-one billion, three hundred sixty-four million, two hundred twenty-one thousand, four hundred fifty-six".