261543657 has 8 divisors (see below), whose sum is σ = 369238176. Its totient is φ = 164105792.

The previous prime is 261543619. The next prime is 261543671. The reversal of 261543657 is 756345162.

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 261543657 - 2²⁴ = 244766441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261543617) 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, 2564103 + ... + 2564204.

It is an arithmetic number, because the mean of its divisors is an integer number (46154772).

Almost surely, 2^261543657 is an apocalyptic number.

It is an amenable number.

261543657 is a deficient number, since it is larger than the sum of its proper divisors (107694519).

261543657 is a wasteful number, since it uses less digits than its factorization.

261543657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5128327.

The product of its digits is 151200, while the sum is 39.

The square root of 261543657 is about 16172.3114303429. The cubic root of 261543657 is about 639.5110661856.

The spelling of 261543657 in words is "two hundred sixty-one million, five hundred forty-three thousand, six hundred fifty-seven".