21528534 has 24 divisors (see below), whose sum is σ = 43596072. Its totient is φ = 7087360.

The previous prime is 21528517. The next prime is 21528553. The reversal of 21528534 is 43582512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 76474 + ... + 76754.

It is an arithmetic number, because the mean of its divisors is an integer number (1816503).

Almost surely, 2^21528534 is an apocalyptic number.

21528534 is an abundant number, since it is smaller than the sum of its proper divisors (22067538).

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

21528534 is a wasteful number, since it uses less digits than its factorization.

21528534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512 (or 399 counting only the distinct ones).

The product of its digits is 9600, while the sum is 30.

The square root of 21528534 is about 4639.8851278884. The cubic root of 21528534 is about 278.1878464047.

The spelling of 21528534 in words is "twenty-one million, five hundred twenty-eight thousand, five hundred thirty-four".