21505492 has 36 divisors (see below), whose sum is σ = 40613076. Its totient is φ = 9959040.

The previous prime is 21505481. The next prime is 21505499. The reversal of 21505492 is 29450512.

It can be written as a sum of positive squares in 2 ways, for example, as 15023376 + 6482116 = 3876^2 + 2546^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21505492.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505499) 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, 76392 + ... + 76672.

It is an arithmetic number, because the mean of its divisors is an integer number (1128141).

Almost surely, 2^21505492 is an apocalyptic number.

It is an amenable number.

21505492 is a deficient number, since it is larger than the sum of its proper divisors (19107584).

21505492 is a wasteful number, since it uses less digits than its factorization.

21505492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 376 (or 355 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 21505492 is about 4637.4014275238. The cubic root of 21505492 is about 278.0885627812.

The spelling of 21505492 in words is "twenty-one million, five hundred five thousand, four hundred ninety-two".