261553751 has 2 divisors, whose sum is σ = 261553752. Its totient is φ = 261553750.

The previous prime is 261553739. The next prime is 261553759. The reversal of 261553751 is 157355162.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261553751 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261553759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130776875 + 130776876.

It is an arithmetic number, because the mean of its divisors is an integer number (130776876).

Almost surely, 2^261553751 is an apocalyptic number.

261553751 is a deficient number, since it is larger than the sum of its proper divisors (1).

261553751 is an equidigital number, since it uses as much as digits as its factorization.

261553751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31500, while the sum is 35.

The square root of 261553751 is about 16172.6235039340. The cubic root of 261553751 is about 639.5192931635.

The spelling of 261553751 in words is "two hundred sixty-one million, five hundred fifty-three thousand, seven hundred fifty-one".