87567821 has 10 divisors (see below), whose sum is σ = 96340110. Its totient is φ = 79593800.

The previous prime is 87567803. The next prime is 87567847. The reversal of 87567821 is 12876578.

It can be written as a sum of positive squares in only one way, i.e., 50965321 + 36602500 = 7139^2 + 6050^2 .

It is not a de Polignac number, because 87567821 - 2¹⁴ = 87551437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87567871) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 11651 + ... + 17631.

It is an arithmetic number, because the mean of its divisors is an integer number (9634011).

Almost surely, 2^87567821 is an apocalyptic number.

It is an amenable number.

87567821 is a deficient number, since it is larger than the sum of its proper divisors (8772289).

87567821 is an frugal number, since it uses more digits than its factorization.

87567821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6025 (or 5992 counting only the distinct ones).

The product of its digits is 188160, while the sum is 44.

The square root of 87567821 is about 9357.7679496769. The cubic root of 87567821 is about 444.0666732248.

It can be divided in two parts, 87567 and 821, that added together give a palindrome (88388).

The spelling of 87567821 in words is "eighty-seven million, five hundred sixty-seven thousand, eight hundred twenty-one".