261563770 has 32 divisors (see below), whose sum is σ = 510935040. Its totient is φ = 95833920.

The previous prime is 261563761. The next prime is 261563777. The reversal of 261563770 is 77365162.

It is a super-2 number, since 2×261563770² = 136831211553225800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261563777) 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, 9351 + ... + 24709.

It is an arithmetic number, because the mean of its divisors is an integer number (15966720).

Almost surely, 2^261563770 is an apocalyptic number.

261563770 is a deficient number, since it is larger than the sum of its proper divisors (249371270).

261563770 is a wasteful number, since it uses less digits than its factorization.

261563770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15510.

The product of its (nonzero) digits is 52920, while the sum is 37.

The square root of 261563770 is about 16172.9332528147. The cubic root of 261563770 is about 639.5274588043.

It can be divided in two parts, 26 and 1563770, that added together give a triangular number (1563796 = T₁₇₆₈).

The spelling of 261563770 in words is "two hundred sixty-one million, five hundred sixty-three thousand, seven hundred seventy".