261651641 has 16 divisors (see below), whose sum is σ = 292737600. Its totient is φ = 233216064.

The previous prime is 261651629. The next prime is 261651653. The reversal of 261651641 is 146156162.

It is an interprime number because it is at equal distance from previous prime (261651629) and next prime (261651653).

It is a de Polignac number, because none of the positive numbers 2^k-261651641 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261651598 and 261651607.

It is not an unprimeable number, because it can be changed into a prime (261651661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 91946 + ... + 94748.

It is an arithmetic number, because the mean of its divisors is an integer number (18296100).

Almost surely, 2^261651641 is an apocalyptic number.

It is an amenable number.

261651641 is a deficient number, since it is larger than the sum of its proper divisors (31085959).

261651641 is an equidigital number, since it uses as much as digits as its factorization.

261651641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2873 (or 2839 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 261651641 is about 16175.6496314677. The cubic root of 261651641 is about 639.5990661038.

The spelling of 261651641 in words is "two hundred sixty-one million, six hundred fifty-one thousand, six hundred forty-one".