102542821 has 2 divisors, whose sum is σ = 102542822. Its totient is φ = 102542820.

The previous prime is 102542819. The next prime is 102542833. The reversal of 102542821 is 128245201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 99700225 + 2842596 = 9985^2 + 1686^2 .

It is a cyclic number.

It is not a de Polignac number, because 102542821 - 2¹ = 102542819 is a prime.

Together with 102542819, 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 (102542021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51271410 + 51271411.

It is an arithmetic number, because the mean of its divisors is an integer number (51271411).

Almost surely, 2^102542821 is an apocalyptic number.

It is an amenable number.

102542821 is a deficient number, since it is larger than the sum of its proper divisors (1).

102542821 is an equidigital number, since it uses as much as digits as its factorization.

102542821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 102542821 is about 10126.3429232868. The cubic root of 102542821 is about 468.0602428720.

The spelling of 102542821 in words is "one hundred two million, five hundred forty-two thousand, eight hundred twenty-one".