102131221 has 4 divisors (see below), whose sum is σ = 102555244. Its totient is φ = 101707200.

The previous prime is 102131219. The next prime is 102131231. The reversal of 102131221 is 122131201.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122131201 = 127 ⋅961663.

It can be written as a sum of positive squares in 2 ways, for example, as 67486225 + 34644996 = 8215^2 + 5886^2 .

It is a cyclic number.

It is not a de Polignac number, because 102131221 - 2¹ = 102131219 is a prime.

It is a super-3 number, since 3×102131221³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102131231) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 211650 + ... + 212131.

It is an arithmetic number, because the mean of its divisors is an integer number (25638811).

Almost surely, 2^102131221 is an apocalyptic number.

It is an amenable number.

102131221 is a deficient number, since it is larger than the sum of its proper divisors (424023).

102131221 is an equidigital number, since it uses as much as digits as its factorization.

102131221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424022.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 102131221 is about 10105.9992578666. Note that the first 3 decimals coincide. The cubic root of 102131221 is about 467.4331489528.

Adding to 102131221 its reverse (122131201), we get a palindrome (224262422).

The spelling of 102131221 in words is "one hundred two million, one hundred thirty-one thousand, two hundred twenty-one".