21000734 has 4 divisors (see below), whose sum is σ = 31501104. Its totient is φ = 10500366.

The previous prime is 21000731. The next prime is 21000737. The reversal of 21000734 is 43700012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21000731) and next prime (21000737).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5250182 + ... + 5250185.

It is an arithmetic number, because the mean of its divisors is an integer number (7875276).

Almost surely, 2^21000734 is an apocalyptic number.

21000734 is a deficient number, since it is larger than the sum of its proper divisors (10500370).

21000734 is a wasteful number, since it uses less digits than its factorization.

21000734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10500369.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 21000734 is about 4582.6557802218. The cubic root of 21000734 is about 275.8956319663.

Adding to 21000734 its reverse (43700012), we get a palindrome (64700746).

The spelling of 21000734 in words is "twenty-one million, seven hundred thirty-four", and thus it is an aban number.