102120021 has 24 divisors (see below), whose sum is σ = 154365120. Its totient is φ = 67459392.

The previous prime is 102120017. The next prime is 102120043. The reversal of 102120021 is 120021201.

It is not a de Polignac number, because 102120021 - 2² = 102120017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 102119985 and 102120012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102120001) 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 in 23 ways as a sum of consecutive naturals, for example, 25600 + ... + 29318.

It is an arithmetic number, because the mean of its divisors is an integer number (6431880).

Almost surely, 2^102120021 is an apocalyptic number.

It is an amenable number.

102120021 is a deficient number, since it is larger than the sum of its proper divisors (52245099).

102120021 is an equidigital number, since it uses as much as digits as its factorization.

102120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3847 (or 3835 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 102120021 is about 10105.4451163717. The cubic root of 102120021 is about 467.4160616456.

Adding to 102120021 its reverse (120021201), we get a palindrome (222141222).

The spelling of 102120021 in words is "one hundred two million, one hundred twenty thousand, twenty-one".