21001234 has 4 divisors (see below), whose sum is σ = 31501854. Its totient is φ = 10500616.

The previous prime is 21001187. The next prime is 21001247. The reversal of 21001234 is 43210012.

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

It can be written as a sum of positive squares in only one way, i.e., 13300609 + 7700625 = 3647^2 + 2775^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5250307 + ... + 5250310.

Almost surely, 2^21001234 is an apocalyptic number.

21001234 is a deficient number, since it is larger than the sum of its proper divisors (10500620).

21001234 is a wasteful number, since it uses less digits than its factorization.

21001234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10500619.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21001234 is about 4582.7103334162. The cubic root of 21001234 is about 275.8978215203.

Adding to 21001234 its reverse (43210012), we get a palindrome (64211246).

The spelling of 21001234 in words is "twenty-one million, one thousand, two hundred thirty-four".