129821491 has 4 divisors (see below), whose sum is σ = 129889984. Its totient is φ = 129753000.

The previous prime is 129821437. The next prime is 129821501. The reversal of 129821491 is 194128921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 194128921 = 7 ⋅27732703.

It is a cyclic number.

It is not a de Polignac number, because 129821491 - 2²¹ = 127724339 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 129821491.

It is not an unprimeable number, because it can be changed into a prime (129821891) 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, 31320 + ... + 35221.

It is an arithmetic number, because the mean of its divisors is an integer number (32472496).

Almost surely, 2^129821491 is an apocalyptic number.

129821491 is a deficient number, since it is larger than the sum of its proper divisors (68493).

129821491 is an equidigital number, since it uses as much as digits as its factorization.

129821491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68492.

The product of its digits is 10368, while the sum is 37.

The square root of 129821491 is about 11393.9234243521. The cubic root of 129821491 is about 506.3477263758.

The spelling of 129821491 in words is "one hundred twenty-nine million, eight hundred twenty-one thousand, four hundred ninety-one".