21000046 has 4 divisors (see below), whose sum is σ = 31500072. Its totient is φ = 10500022.

The previous prime is 21000041. The next prime is 21000059. The reversal of 21000046 is 64000012.

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

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5250010 + ... + 5250013.

It is an arithmetic number, because the mean of its divisors is an integer number (7875018).

Almost surely, 2^21000046 is an apocalyptic number.

21000046 is a deficient number, since it is larger than the sum of its proper divisors (10500026).

21000046 is a wasteful number, since it uses less digits than its factorization.

21000046 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10500025.

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

The square root of 21000046 is about 4582.5807139646. The cubic root of 21000046 is about 275.8926190832.

Adding to 21000046 its reverse (64000012), we get a palindrome (85000058).

The spelling of 21000046 in words is "twenty-one million, forty-six", and thus it is an aban number and an uban number.