87721261 has 4 divisors (see below), whose sum is σ = 87774300. Its totient is φ = 87668224.

The previous prime is 87721243. The next prime is 87721267. The reversal of 87721261 is 16212778.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16212778 = 2 ⋅8106389.

It can be written as a sum of positive squares in 2 ways, for example, as 47955625 + 39765636 = 6925^2 + 6306^2 .

It is a cyclic number.

It is not a de Polignac number, because 87721261 - 2⁷ = 87721133 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 (87721267) 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 3 ways as a sum of consecutive naturals, for example, 23956 + ... + 27373.

It is an arithmetic number, because the mean of its divisors is an integer number (21943575).

Almost surely, 2^87721261 is an apocalyptic number.

It is an amenable number.

87721261 is a deficient number, since it is larger than the sum of its proper divisors (53039).

87721261 is a wasteful number, since it uses less digits than its factorization.

87721261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53038.

The product of its digits is 9408, while the sum is 34.

The square root of 87721261 is about 9365.9628976417. The cubic root of 87721261 is about 444.3258926139.

The spelling of 87721261 in words is "eighty-seven million, seven hundred twenty-one thousand, two hundred sixty-one".