261299766 has 32 divisors (see below), whose sum is σ = 643200768. Its totient is φ = 68914080.

The previous prime is 261299693. The next prime is 261299767. The reversal of 261299766 is 667992162.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261299767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 238740 + ... + 239831.

It is an arithmetic number, because the mean of its divisors is an integer number (20100024).

Almost surely, 2^261299766 is an apocalyptic number.

261299766 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

261299766 is an abundant number, since it is smaller than the sum of its proper divisors (381901002).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261299766 is a wasteful number, since it uses less digits than its factorization.

261299766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478596.

The product of its digits is 489888, while the sum is 48.

The square root of 261299766 is about 16164.7692838469. The cubic root of 261299766 is about 639.3122217534.

It can be divided in two parts, 2612 and 99766, that added together give a triangular number (102378 = T₄₅₂).

The spelling of 261299766 in words is "two hundred sixty-one million, two hundred ninety-nine thousand, seven hundred sixty-six".