21129381215 has 8 divisors (see below), whose sum is σ = 25384174080. Its totient is φ = 16884227232.

The previous prime is 21129381191. The next prime is 21129381257. The reversal of 21129381215 is 51218392112.

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 21129381215 - 2¹⁶ = 21129315679 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2404895 + ... + 2413664.

It is an arithmetic number, because the mean of its divisors is an integer number (3173021760).

Almost surely, 2^21129381215 is an apocalyptic number.

21129381215 is a deficient number, since it is larger than the sum of its proper divisors (4254792865).

21129381215 is an equidigital number, since it uses as much as digits as its factorization.

21129381215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4819441.

The product of its digits is 8640, while the sum is 35.

The spelling of 21129381215 in words is "twenty-one billion, one hundred twenty-nine million, three hundred eighty-one thousand, two hundred fifteen".