102181421 has 2 divisors, whose sum is σ = 102181422. Its totient is φ = 102181420.

The previous prime is 102181399. The next prime is 102181423. The reversal of 102181421 is 124181201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 101808100 + 373321 = 10090^2 + 611^2 .

It is a cyclic number.

It is not a de Polignac number, because 102181421 - 2²² = 97987117 is a prime.

Together with 102181423, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 102181393 and 102181402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (102181423) 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 as a sum of consecutive naturals, namely, 51090710 + 51090711.

It is an arithmetic number, because the mean of its divisors is an integer number (51090711).

Almost surely, 2^102181421 is an apocalyptic number.

It is an amenable number.

102181421 is a deficient number, since it is larger than the sum of its proper divisors (1).

102181421 is an equidigital number, since it uses as much as digits as its factorization.

102181421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 102181421 is about 10108.4826259929. The cubic root of 102181421 is about 467.5097213608.

The spelling of 102181421 in words is "one hundred two million, one hundred eighty-one thousand, four hundred twenty-one".