87155221 has 2 divisors, whose sum is σ = 87155222. Its totient is φ = 87155220.

The previous prime is 87155197. The next prime is 87155287. The reversal of 87155221 is 12255178.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87142225 + 12996 = 9335^2 + 114^2 .

It is a cyclic number.

It is not a de Polignac number, because 87155221 - 2⁷ = 87155093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87153221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43577610 + 43577611.

It is an arithmetic number, because the mean of its divisors is an integer number (43577611).

Almost surely, 2^87155221 is an apocalyptic number.

It is an amenable number.

87155221 is a deficient number, since it is larger than the sum of its proper divisors (1).

87155221 is an equidigital number, since it uses as much as digits as its factorization.

87155221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5600, while the sum is 31.

The square root of 87155221 is about 9335.6960640329. The cubic root of 87155221 is about 443.3681273061.

The spelling of 87155221 in words is "eighty-seven million, one hundred fifty-five thousand, two hundred twenty-one".