87506721 has 6 divisors (see below), whose sum is σ = 126398610. Its totient is φ = 58337808.

The previous prime is 87506663. The next prime is 87506729. The reversal of 87506721 is 12760578.

87506721 is a `hidden beast` number, since 87 + 506 + 72 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 76317696 + 11189025 = 8736^2 + 3345^2 .

It is not a de Polignac number, because 87506721 - 2¹³ = 87498529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (87506729) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4861476 + ... + 4861493.

It is an arithmetic number, because the mean of its divisors is an integer number (21066435).

Almost surely, 2^87506721 is an apocalyptic number.

It is an amenable number.

87506721 is a deficient number, since it is larger than the sum of its proper divisors (38891889).

87506721 is a wasteful number, since it uses less digits than its factorization.

87506721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9722975 (or 9722972 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 87506721 is about 9354.5027125978. The cubic root of 87506721 is about 443.9633674427.

The spelling of 87506721 in words is "eighty-seven million, five hundred six thousand, seven hundred twenty-one".