87242821 has 2 divisors, whose sum is σ = 87242822. Its totient is φ = 87242820.

The previous prime is 87242819. The next prime is 87242839. The reversal of 87242821 is 12824278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52562500 + 34680321 = 7250^2 + 5889^2 .

It is a cyclic number.

It is not a de Polignac number, because 87242821 - 2¹ = 87242819 is a prime.

It is a super-2 number, since 2×87242821² = 15222619632076082, which contains 22 as substring.

Together with 87242819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87242021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43621410 + 43621411.

It is an arithmetic number, because the mean of its divisors is an integer number (43621411).

Almost surely, 2^87242821 is an apocalyptic number.

It is an amenable number.

87242821 is a deficient number, since it is larger than the sum of its proper divisors (1).

87242821 is an equidigital number, since it uses as much as digits as its factorization.

87242821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14336, while the sum is 34.

The square root of 87242821 is about 9340.3865551700. The cubic root of 87242821 is about 443.5166211555.

The spelling of 87242821 in words is "eighty-seven million, two hundred forty-two thousand, eight hundred twenty-one".