261091290 has 32 divisors (see below), whose sum is σ = 633666240. Its totient is φ = 68841344.

The previous prime is 261091283. The next prime is 261091291. The reversal of 261091290 is 92190162.

It is a happy number.

It is a super-3 number, since 3×261091290³ (a number of 26 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (261091291) 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, 46224 + ... + 51563.

It is an arithmetic number, because the mean of its divisors is an integer number (19802070).

Almost surely, 2^261091290 is an apocalyptic number.

261091290 is an abundant number, since it is smaller than the sum of its proper divisors (372574950).

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

261091290 is a wasteful number, since it uses less digits than its factorization.

261091290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97886.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 261091290 is about 16158.3195289609. The cubic root of 261091290 is about 639.1421530768.

The spelling of 261091290 in words is "two hundred sixty-one million, ninety-one thousand, two hundred ninety".