87639661 has 4 divisors (see below), whose sum is σ = 87723324. Its totient is φ = 87556000.

The previous prime is 87639659. The next prime is 87639689. The reversal of 87639661 is 16693678.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16693678 = 2 ⋅8346839.

It can be written as a sum of positive squares in 2 ways, for example, as 40717161 + 46922500 = 6381^2 + 6850^2 .

It is a cyclic number.

It is not a de Polignac number, because 87639661 - 2¹ = 87639659 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 (87639611) 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, 40240 + ... + 42361.

It is an arithmetic number, because the mean of its divisors is an integer number (21930831).

Almost surely, 2^87639661 is an apocalyptic number.

It is an amenable number.

87639661 is a deficient number, since it is larger than the sum of its proper divisors (83663).

87639661 is a wasteful number, since it uses less digits than its factorization.

87639661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83662.

The product of its digits is 326592, while the sum is 46.

The square root of 87639661 is about 9361.6056849239. The cubic root of 87639661 is about 444.1880763819.

The spelling of 87639661 in words is "eighty-seven million, six hundred thirty-nine thousand, six hundred sixty-one".