261420641 has 8 divisors (see below), whose sum is σ = 264892680. Its totient is φ = 257969152.

The previous prime is 261420637. The next prime is 261420647. The reversal of 261420641 is 146024162.

It can be written as a sum of positive squares in 4 ways, for example, as 15840400 + 245580241 = 3980^2 + 15671^2 .

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 261420641 - 2² = 261420637 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261420641.

It is not an unprimeable number, because it can be changed into a prime (261420647) 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, 21365 + ... + 31293.

It is an arithmetic number, because the mean of its divisors is an integer number (33111585).

Almost surely, 2^261420641 is an apocalyptic number.

It is an amenable number.

261420641 is a deficient number, since it is larger than the sum of its proper divisors (3472039).

261420641 is a wasteful number, since it uses less digits than its factorization.

261420641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10275.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 261420641 is about 16168.5076924248. The cubic root of 261420641 is about 639.4107866484.

The spelling of 261420641 in words is "two hundred sixty-one million, four hundred twenty thousand, six hundred forty-one".