261209005 has 8 divisors (see below), whose sum is σ = 313761024. Its totient is φ = 208760400.

The previous prime is 261208993. The next prime is 261209009. The reversal of 261209005 is 500902162.

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

It is not a de Polignac number, because 261209005 - 2⁵ = 261208973 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 (261209009) 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, 20181 + ... + 30490.

It is an arithmetic number, because the mean of its divisors is an integer number (39220128).

Almost surely, 2^261209005 is an apocalyptic number.

It is an amenable number.

261209005 is a deficient number, since it is larger than the sum of its proper divisors (52552019).

261209005 is a wasteful number, since it uses less digits than its factorization.

261209005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51707.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 261209005 is about 16161.9616693024. The cubic root of 261209005 is about 639.2381926834.

The spelling of 261209005 in words is "two hundred sixty-one million, two hundred nine thousand, five".