285091381 has 4 divisors (see below), whose sum is σ = 285127200. Its totient is φ = 285055564.

The previous prime is 285091379. The next prime is 285091393. The reversal of 285091381 is 183190582.

285091381 is a nontrivial binomial coefficient, being equal to C(23879, 2).

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 285091381 - 2¹ = 285091379 is a prime.

It is a super-2 number, since 2×285091381² = 162554191040974322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 285091381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (285191381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 23878.

It is an arithmetic number, because the mean of its divisors is an integer number (71281800).

Almost surely, 2^285091381 is an apocalyptic number.

285091381 is the 23878-th triangular number.

285091381 is the 7960-th centered nonagonal number.

It is an amenable number.

285091381 is a deficient number, since it is larger than the sum of its proper divisors (35819).

285091381 is a wasteful number, since it uses less digits than its factorization.

285091381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35818.

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 285091381 is about 16884.6492708614. The cubic root of 285091381 is about 658.1547639952.

It can be divided in two parts, 28509 and 1381, that added together give a triangular number (29890 = T₂₄₄).

The spelling of 285091381 in words is "two hundred eighty-five million, ninety-one thousand, three hundred eighty-one".