87851781 has 6 divisors (see below), whose sum is σ = 126897030. Its totient is φ = 58567848.

The previous prime is 87851747. The next prime is 87851783. The reversal of 87851781 is 18715878.

It can be written as a sum of positive squares in only one way, i.e., 59814756 + 28037025 = 7734^2 + 5295^2 .

It is not a de Polignac number, because 87851781 - 2¹³ = 87843589 is a prime.

It is a super-2 number, since 2×87851781² = 15435870849743922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87851783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4880646 + ... + 4880663.

It is an arithmetic number, because the mean of its divisors is an integer number (21149505).

Almost surely, 2^87851781 is an apocalyptic number.

It is an amenable number.

87851781 is a deficient number, since it is larger than the sum of its proper divisors (39045249).

87851781 is a wasteful number, since it uses less digits than its factorization.

87851781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9761315 (or 9761312 counting only the distinct ones).

The product of its digits is 125440, while the sum is 45.

The square root of 87851781 is about 9372.9280910503. The cubic root of 87851781 is about 444.5461534564.

The spelling of 87851781 in words is "eighty-seven million, eight hundred fifty-one thousand, seven hundred eighty-one".