261663487 has 2 divisors, whose sum is σ = 261663488. Its totient is φ = 261663486.

The previous prime is 261663481. The next prime is 261663499. The reversal of 261663487 is 784366162.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261663487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261663481) 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, 130831743 + 130831744.

It is an arithmetic number, because the mean of its divisors is an integer number (130831744).

Almost surely, 2^261663487 is an apocalyptic number.

261663487 is a deficient number, since it is larger than the sum of its proper divisors (1).

261663487 is an equidigital number, since it uses as much as digits as its factorization.

261663487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 43.

The square root of 261663487 is about 16176.0157949972. The cubic root of 261663487 is about 639.6087183475.

The spelling of 261663487 in words is "two hundred sixty-one million, six hundred sixty-three thousand, four hundred eighty-seven".