21129396 has 12 divisors (see below), whose sum is σ = 49301952. Its totient is φ = 7043128.

The previous prime is 21129379. The next prime is 21129403. The reversal of 21129396 is 69392112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 880380 + ... + 880403.

It is an arithmetic number, because the mean of its divisors is an integer number (4108496).

Almost surely, 2^21129396 is an apocalyptic number.

It is an amenable number.

21129396 is an abundant number, since it is smaller than the sum of its proper divisors (28172556).

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

21129396 is a wasteful number, since it uses less digits than its factorization.

21129396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1760790 (or 1760788 counting only the distinct ones).

The product of its digits is 5832, while the sum is 33.

The square root of 21129396 is about 4596.6722745917. The cubic root of 21129396 is about 276.4579144973.

The spelling of 21129396 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred ninety-six".