102021989 has 2 divisors, whose sum is σ = 102021990. Its totient is φ = 102021988.

The previous prime is 102021977. The next prime is 102021991. The reversal of 102021989 is 989120201.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69588964 + 32433025 = 8342^2 + 5695^2 .

It is a cyclic number.

It is not a de Polignac number, because 102021989 - 2²⁰ = 100973413 is a prime.

It is a super-2 number, since 2×102021989² = 20816972479032242, which contains 22 as substring.

Together with 102021991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (102021919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51010994 + 51010995.

It is an arithmetic number, because the mean of its divisors is an integer number (51010995).

Almost surely, 2^102021989 is an apocalyptic number.

It is an amenable number.

102021989 is a deficient number, since it is larger than the sum of its proper divisors (1).

102021989 is an equidigital number, since it uses as much as digits as its factorization.

102021989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 102021989 is about 10100.5934974139. The cubic root of 102021989 is about 467.2664455331.

The spelling of 102021989 in words is "one hundred two million, twenty-one thousand, nine hundred eighty-nine".