261563387 has 2 divisors, whose sum is σ = 261563388. Its totient is φ = 261563386.

The previous prime is 261563369. The next prime is 261563447. The reversal of 261563387 is 783365162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261563387 - 2¹⁴ = 261547003 is a prime.

It is a Chen prime.

It is equal to p_14276678 and since 261563387 and 14276678 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (261563347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130781693 + 130781694.

It is an arithmetic number, because the mean of its divisors is an integer number (130781694).

Almost surely, 2^261563387 is an apocalyptic number.

261563387 is a deficient number, since it is larger than the sum of its proper divisors (1).

261563387 is an equidigital number, since it uses as much as digits as its factorization.

261563387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 41.

The square root of 261563387 is about 16172.9214120393. The cubic root of 261563387 is about 639.5271466572.

The spelling of 261563387 in words is "two hundred sixty-one million, five hundred sixty-three thousand, three hundred eighty-seven".