87721638 has 16 divisors (see below), whose sum is σ = 176606976. Its totient is φ = 29046600.

The previous prime is 87721637. The next prime is 87721643. The reversal of 87721638 is 83612778.

It is a self number, because there is not a number n which added to its sum of digits gives 87721638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87721633) 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 7 ways as a sum of consecutive naturals, for example, 47506 + ... + 49317.

It is an arithmetic number, because the mean of its divisors is an integer number (11037936).

Almost surely, 2^87721638 is an apocalyptic number.

87721638 is an abundant number, since it is smaller than the sum of its proper divisors (88885338).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

87721638 is a wasteful number, since it uses less digits than its factorization.

87721638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96979.

The product of its digits is 112896, while the sum is 42.

The square root of 87721638 is about 9365.9830236874. The cubic root of 87721638 is about 444.3265291400.

The spelling of 87721638 in words is "eighty-seven million, seven hundred twenty-one thousand, six hundred thirty-eight".