87212721 has 8 divisors (see below), whose sum is σ = 116464320. Its totient is φ = 58051472.

The previous prime is 87212707. The next prime is 87212789. The reversal of 87212721 is 12721278.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 87212721 - 2¹³ = 87204529 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (87211721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20301 + ... + 24218.

It is an arithmetic number, because the mean of its divisors is an integer number (14558040).

Almost surely, 2^87212721 is an apocalyptic number.

It is an amenable number.

87212721 is a deficient number, since it is larger than the sum of its proper divisors (29251599).

87212721 is a wasteful number, since it uses less digits than its factorization.

87212721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45175.

The product of its digits is 3136, while the sum is 30.

The square root of 87212721 is about 9338.7751338171. The cubic root of 87212721 is about 443.4656087982.

Adding to 87212721 its reverse (12721278), we get a palindrome (99933999).

The spelling of 87212721 in words is "eighty-seven million, two hundred twelve thousand, seven hundred twenty-one".