21129534 has 24 divisors (see below), whose sum is σ = 45903312. Its totient is φ = 7024320.

The previous prime is 21129533. The next prime is 21129547. The reversal of 21129534 is 43592112.

21129534 is a `hidden beast` number, since 2 + 1 + 129 + 534 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21129498 and 21129507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21129533) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6439 + ... + 9149.

It is an arithmetic number, because the mean of its divisors is an integer number (1912638).

Almost surely, 2^21129534 is an apocalyptic number.

21129534 is an abundant number, since it is smaller than the sum of its proper divisors (24773778).

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

21129534 is a wasteful number, since it uses less digits than its factorization.

21129534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3152 (or 3149 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21129534 is about 4596.6872854263. The cubic root of 21129534 is about 276.4585163619.

The spelling of 21129534 in words is "twenty-one million, one hundred twenty-nine thousand, five hundred thirty-four".