261621569 has 8 divisors (see below), whose sum is σ = 285526560. Its totient is φ = 237736800.

The previous prime is 261621559. The next prime is 261621587. The reversal of 261621569 is 965126162.

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 261621569 - 2⁴ = 261621553 is a prime.

It is a super-2 number, since 2×261621569² = 136891690732043522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261621509) 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, 37949 + ... + 44309.

It is an arithmetic number, because the mean of its divisors is an integer number (35690820).

Almost surely, 2^261621569 is an apocalyptic number.

It is an amenable number.

261621569 is a deficient number, since it is larger than the sum of its proper divisors (23904991).

261621569 is a wasteful number, since it uses less digits than its factorization.

261621569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10111.

The product of its digits is 38880, while the sum is 38.

The square root of 261621569 is about 16174.7200594013. The cubic root of 261621569 is about 639.5745618176.

The spelling of 261621569 in words is "two hundred sixty-one million, six hundred twenty-one thousand, five hundred sixty-nine".