21205734 has 24 divisors (see below), whose sum is σ = 46619160. Its totient is φ = 6425760.

The previous prime is 21205727. The next prime is 21205759. The reversal of 21205734 is 43750212.

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, 13879 + ... + 15330.

It is an arithmetic number, because the mean of its divisors is an integer number (1942465).

Almost surely, 2^21205734 is an apocalyptic number.

21205734 is an abundant number, since it is smaller than the sum of its proper divisors (25413426).

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

21205734 is a wasteful number, since it uses less digits than its factorization.

21205734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29236 (or 29225 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21205734 is about 4604.9684038004. The cubic root of 21205734 is about 276.7904508912.

Adding to 21205734 its reverse (43750212), we get a palindrome (64955946).

The spelling of 21205734 in words is "twenty-one million, two hundred five thousand, seven hundred thirty-four".