87636721 has 24 divisors (see below), whose sum is σ = 98316288. Its totient is φ = 77976000.

The previous prime is 87636713. The next prime is 87636727. The reversal of 87636721 is 12763678.

It is not a de Polignac number, because 87636721 - 2³ = 87636713 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87636727) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 458736 + ... + 458926.

It is an arithmetic number, because the mean of its divisors is an integer number (4096512).

Almost surely, 2^87636721 is an apocalyptic number.

87636721 is the 5921-st heptagonal number.

It is an amenable number.

87636721 is a deficient number, since it is larger than the sum of its proper divisors (10679567).

87636721 is a wasteful number, since it uses less digits than its factorization.

87636721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301 (or 282 counting only the distinct ones).

The product of its digits is 84672, while the sum is 40.

The square root of 87636721 is about 9361.4486592621. The cubic root of 87636721 is about 444.1831093478.

The spelling of 87636721 in words is "eighty-seven million, six hundred thirty-six thousand, seven hundred twenty-one".