261356247 has 8 divisors (see below), whose sum is σ = 387194480. Its totient is φ = 174237480.

The previous prime is 261356219. The next prime is 261356287. The reversal of 261356247 is 742653162.

261356247 is a `hidden beast` number, since 2 + 61 + 356 + 247 = 666.

It is not a de Polignac number, because 261356247 - 2¹⁰ = 261355223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261356287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4839904 + ... + 4839957.

It is an arithmetic number, because the mean of its divisors is an integer number (48399310).

Almost surely, 2^261356247 is an apocalyptic number.

261356247 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

261356247 is a deficient number, since it is larger than the sum of its proper divisors (125838233).

261356247 is an equidigital number, since it uses as much as digits as its factorization.

261356247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9679870 (or 9679864 counting only the distinct ones).

The product of its digits is 60480, while the sum is 36.

The square root of 261356247 is about 16166.5162295406. The cubic root of 261356247 is about 639.3582817414.

The spelling of 261356247 in words is "two hundred sixty-one million, three hundred fifty-six thousand, two hundred forty-seven".