21208734 has 12 divisors (see below), whose sum is σ = 45952296. Its totient is φ = 7069572.

The previous prime is 21208729. The next prime is 21208739. The reversal of 21208734 is 43780212.

It is an interprime number because it is at equal distance from previous prime (21208729) and next prime (21208739).

It is a junction number, because it is equal to n+sod(n) for n = 21208698 and 21208707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21208739) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 589114 + ... + 589149.

It is an arithmetic number, because the mean of its divisors is an integer number (3829358).

Almost surely, 2^21208734 is an apocalyptic number.

21208734 is an abundant number, since it is smaller than the sum of its proper divisors (24743562).

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

21208734 is a wasteful number, since it uses less digits than its factorization.

21208734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1178271 (or 1178268 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21208734 is about 4605.2941274147. The cubic root of 21208734 is about 276.8035028987.

Adding to 21208734 its reverse (43780212), we get a palindrome (64988946).

The spelling of 21208734 in words is "twenty-one million, two hundred eight thousand, seven hundred thirty-four".