129699021 has 4 divisors (see below), whose sum is σ = 172932032. Its totient is φ = 86466012.

The previous prime is 129699013. The next prime is 129699029. The reversal of 129699021 is 120996921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (129699013) and next prime (129699029).

It is not a de Polignac number, because 129699021 - 2³ = 129699013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129699029) 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, 21616501 + ... + 21616506.

It is an arithmetic number, because the mean of its divisors is an integer number (43233008).

Almost surely, 2^129699021 is an apocalyptic number.

It is an amenable number.

129699021 is a deficient number, since it is larger than the sum of its proper divisors (43233011).

129699021 is an equidigital number, since it uses as much as digits as its factorization.

129699021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43233010.

The product of its (nonzero) digits is 17496, while the sum is 39.

The square root of 129699021 is about 11388.5478003124. The cubic root of 129699021 is about 506.1884514718.

The spelling of 129699021 in words is "one hundred twenty-nine million, six hundred ninety-nine thousand, twenty-one".