261839987 has 4 divisors (see below), whose sum is σ = 261873000. Its totient is φ = 261806976.

The previous prime is 261839983. The next prime is 261840011. The reversal of 261839987 is 789938162.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 261839987 - 2² = 261839983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261839983) 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, 3368 + ... + 23130.

It is an arithmetic number, because the mean of its divisors is an integer number (65468250).

Almost surely, 2^261839987 is an apocalyptic number.

261839987 is a deficient number, since it is larger than the sum of its proper divisors (33013).

261839987 is a wasteful number, since it uses less digits than its factorization.

261839987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33012.

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

The square root of 261839987 is about 16181.4704832410. The cubic root of 261839987 is about 639.7524978851.

The spelling of 261839987 in words is "two hundred sixty-one million, eight hundred thirty-nine thousand, nine hundred eighty-seven".