261855019 has 2 divisors, whose sum is σ = 261855020. Its totient is φ = 261855018.

The previous prime is 261854969. The next prime is 261855037. The reversal of 261855019 is 910558162.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261855019 is a prime.

It is a super-2 number, since 2×261855019² = 137136101950980722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261855719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130927509 + 130927510.

It is an arithmetic number, because the mean of its divisors is an integer number (130927510).

Almost surely, 2^261855019 is an apocalyptic number.

261855019 is a deficient number, since it is larger than the sum of its proper divisors (1).

261855019 is an equidigital number, since it uses as much as digits as its factorization.

261855019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21600, while the sum is 37.

The square root of 261855019 is about 16181.9349584653. The cubic root of 261855019 is about 639.7647401908.

The spelling of 261855019 in words is "two hundred sixty-one million, eight hundred fifty-five thousand, nineteen".