87721645 has 16 divisors (see below), whose sum is σ = 115032960. Its totient is φ = 63688000.

The previous prime is 87721643. The next prime is 87721657. The reversal of 87721645 is 54612778.

It is not a de Polignac number, because 87721645 - 2¹ = 87721643 is a prime.

It is a super-3 number, since 3×87721645³ (a number of 25 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 87721598 and 87721607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87721643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45195 + ... + 47095.

It is an arithmetic number, because the mean of its divisors is an integer number (7189560).

Almost surely, 2^87721645 is an apocalyptic number.

It is an amenable number.

87721645 is a deficient number, since it is larger than the sum of its proper divisors (27311315).

87721645 is a wasteful number, since it uses less digits than its factorization.

87721645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2756.

The product of its digits is 94080, while the sum is 40.

The square root of 87721645 is about 9365.9833973801. The cubic root of 87721645 is about 444.3265409588.

It can be divided in two parts, 877 and 21645, that added together give a palindrome (22522).

The spelling of 87721645 in words is "eighty-seven million, seven hundred twenty-one thousand, six hundred forty-five".