261973889 has 4 divisors (see below), whose sum is σ = 264292356. Its totient is φ = 259655424.

The previous prime is 261973861. The next prime is 261973967. The reversal of 261973889 is 988379162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46471489 + 215502400 = 6817^2 + 14680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261973889 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 261973889.

It is not an unprimeable number, because it can be changed into a prime (261973189) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1159064 + ... + 1159289.

It is an arithmetic number, because the mean of its divisors is an integer number (66073089).

Almost surely, 2^261973889 is an apocalyptic number.

It is an amenable number.

261973889 is a deficient number, since it is larger than the sum of its proper divisors (2318467).

261973889 is a wasteful number, since it uses less digits than its factorization.

261973889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2318466.

The product of its digits is 1306368, while the sum is 53.

The square root of 261973889 is about 16185.6074646582. The cubic root of 261973889 is about 639.8615333581.

The spelling of 261973889 in words is "two hundred sixty-one million, nine hundred seventy-three thousand, eight hundred eighty-nine".