261553919 has 8 divisors (see below), whose sum is σ = 291403008. Its totient is φ = 232716760.

The previous prime is 261553889. The next prime is 261553921. The reversal of 261553919 is 919355162.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261553919 - 2¹² = 261549823 is a prime.

It is a super-2 number, since 2×261553919² = 136820905088517122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261553939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 252437 + ... + 253470.

It is an arithmetic number, because the mean of its divisors is an integer number (36425376).

Almost surely, 2^261553919 is an apocalyptic number.

261553919 is a deficient number, since it is larger than the sum of its proper divisors (29849089).

261553919 is a wasteful number, since it uses less digits than its factorization.

261553919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505965.

The product of its digits is 72900, while the sum is 41.

The square root of 261553919 is about 16172.6286978957. The cubic root of 261553919 is about 639.5194300878.

The spelling of 261553919 in words is "two hundred sixty-one million, five hundred fifty-three thousand, nine hundred nineteen".