129920028 has 48 divisors (see below), whose sum is σ = 354520320. Its totient is φ = 36255744.

The previous prime is 129920027. The next prime is 129920033. The reversal of 129920028 is 820029921.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129920027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14373 + ... + 21596.

It is an arithmetic number, because the mean of its divisors is an integer number (7385840).

Almost surely, 2^129920028 is an apocalyptic number.

It is an amenable number.

129920028 is an abundant number, since it is smaller than the sum of its proper divisors (224600292).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

129920028 is a wasteful number, since it uses less digits than its factorization.

129920028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36026 (or 36024 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 129920028 is about 11398.2467072792. The cubic root of 129920028 is about 506.4758031869.

Adding to 129920028 its reverse (820029921), we get a palindrome (949949949).

The spelling of 129920028 in words is "one hundred twenty-nine million, nine hundred twenty thousand, twenty-eight".