261231557 has 8 divisors (see below), whose sum is σ = 263297496. Its totient is φ = 259172352.

The previous prime is 261231547. The next prime is 261231559. The reversal of 261231557 is 755132162.

261231557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 242300356 + 18931201 = 15566^2 + 4351^2 .

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 261231557 - 2¹⁸ = 260969413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261231559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 98513 + ... + 101129.

It is an arithmetic number, because the mean of its divisors is an integer number (32912187).

Almost surely, 2^261231557 is an apocalyptic number.

It is an amenable number.

261231557 is a deficient number, since it is larger than the sum of its proper divisors (2065939).

261231557 is a wasteful number, since it uses less digits than its factorization.

261231557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3367.

The product of its digits is 12600, while the sum is 32.

The square root of 261231557 is about 16162.6593418286. The cubic root of 261231557 is about 639.2565887884.

The spelling of 261231557 in words is "two hundred sixty-one million, two hundred thirty-one thousand, five hundred fifty-seven".