129015021 has 8 divisors (see below), whose sum is σ = 172101024. Its totient is φ = 85969520.

The previous prime is 129015001. The next prime is 129015049. The reversal of 129015021 is 120510921.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 129015021 - 2¹⁷ = 128883949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129015001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1686 + ... + 16151.

It is an arithmetic number, because the mean of its divisors is an integer number (21512628).

Almost surely, 2^129015021 is an apocalyptic number.

It is an amenable number.

129015021 is a deficient number, since it is larger than the sum of its proper divisors (43086003).

129015021 is a wasteful number, since it uses less digits than its factorization.

129015021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20251.

The product of its (nonzero) digits is 180, while the sum is 21.

The square root of 129015021 is about 11358.4779350052. The cubic root of 129015021 is about 505.2970457745.

Adding to 129015021 its reverse (120510921), we get a palindrome (249525942).

The spelling of 129015021 in words is "one hundred twenty-nine million, fifteen thousand, twenty-one".