285761981 has 4 divisors (see below), whose sum is σ = 286540992. Its totient is φ = 284982972.

The previous prime is 285761977. The next prime is 285762049. The reversal of 285761981 is 189167582.

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.

It is a cyclic number.

It is not a de Polignac number, because 285761981 - 2² = 285761977 is a prime.

It is a super-2 number, since 2×285761981² = 163319819570088722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (285761951) 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, 388955 + ... + 389688.

It is an arithmetic number, because the mean of its divisors is an integer number (71635248).

Almost surely, 2^285761981 is an apocalyptic number.

It is an amenable number.

285761981 is a deficient number, since it is larger than the sum of its proper divisors (779011).

285761981 is an equidigital number, since it uses as much as digits as its factorization.

285761981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 779010.

The product of its digits is 241920, while the sum is 47.

The square root of 285761981 is about 16904.4958812737. The cubic root of 285761981 is about 658.6704033152.

The spelling of 285761981 in words is "two hundred eighty-five million, seven hundred sixty-one thousand, nine hundred eighty-one".