261443553 has 64 divisors (see below), whose sum is σ = 452198400. Its totient is φ = 130870080.

The previous prime is 261443549. The next prime is 261443557. The reversal of 261443553 is 355344162.

It is an interprime number because it is at equal distance from previous prime (261443549) and next prime (261443557).

It is not a de Polignac number, because 261443553 - 2² = 261443549 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261443557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 284028 + ... + 284946.

It is an arithmetic number, because the mean of its divisors is an integer number (7065600).

Almost surely, 2^261443553 is an apocalyptic number.

261443553 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

261443553 is a deficient number, since it is larger than the sum of its proper divisors (190754847).

261443553 is a wasteful number, since it uses less digits than its factorization.

261443553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002.

The product of its digits is 43200, while the sum is 33.

The square root of 261443553 is about 16169.2162147706. The cubic root of 261443553 is about 639.4294663159.

The spelling of 261443553 in words is "two hundred sixty-one million, four hundred forty-three thousand, five hundred fifty-three".