261220187 has 2 divisors, whose sum is σ = 261220188. Its totient is φ = 261220186.

The previous prime is 261220153. The next prime is 261220217. The reversal of 261220187 is 781022162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261220187 - 2⁶ = 261220123 is a prime.

It is not a weakly prime, because it can be changed into another prime (261270187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130610093 + 130610094.

It is an arithmetic number, because the mean of its divisors is an integer number (130610094).

Almost surely, 2^261220187 is an apocalyptic number.

261220187 is a deficient number, since it is larger than the sum of its proper divisors (1).

261220187 is an equidigital number, since it uses as much as digits as its factorization.

261220187 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 261220187 is about 16162.3076013297. The cubic root of 261220187 is about 639.2473141906.

It can be divided in two parts, 26122018 and 7, that multiplied together give a triangular number (182854126 = T₁₉₁₂₃).

The spelling of 261220187 in words is "two hundred sixty-one million, two hundred twenty thousand, one hundred eighty-seven".