87564781 has 4 divisors (see below), whose sum is σ = 87583612. Its totient is φ = 87545952.

The previous prime is 87564769. The next prime is 87564793. The reversal of 87564781 is 18746578.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (87564769) and next prime (87564793).

It can be written as a sum of positive squares in 2 ways, for example, as 54686025 + 32878756 = 7395^2 + 5734^2 .

It is a cyclic number.

It is not a de Polignac number, because 87564781 - 2¹⁵ = 87532013 is a prime.

It is a super-2 number, since 2×87564781² = 15335181743155922, 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 (87564721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3151 + ... + 13603.

It is an arithmetic number, because the mean of its divisors is an integer number (21895903).

Almost surely, 2^87564781 is an apocalyptic number.

It is an amenable number.

87564781 is a deficient number, since it is larger than the sum of its proper divisors (18831).

87564781 is a wasteful number, since it uses less digits than its factorization.

87564781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18830.

The product of its digits is 376320, while the sum is 46.

The square root of 87564781 is about 9357.6055163701. The cubic root of 87564781 is about 444.0615344334.

It can be divided in two parts, 875 and 64781, that added together give a palindrome (65656).

The spelling of 87564781 in words is "eighty-seven million, five hundred sixty-four thousand, seven hundred eighty-one".