21000027 has 4 divisors (see below), whose sum is σ = 28000040. Its totient is φ = 14000016.

The previous prime is 20999999. The next prime is 21000037. The reversal of 21000027 is 72000012.

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

It is not a de Polignac number, because 21000027 - 2⁷ = 20999899 is a prime.

It is a super-2 number, since 2×21000027² = 882002268001458, which contains 22 as substring.

It is a Duffinian number.

21000027 is a modest number, since divided by 27 gives 21 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 20999976 and 21000021.

It is not an unprimeable number, because it can be changed into a prime (21000037) 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 in 3 ways as a sum of consecutive naturals, for example, 3500002 + ... + 3500007.

It is an arithmetic number, because the mean of its divisors is an integer number (7000010).

Almost surely, 2^21000027 is an apocalyptic number.

21000027 is a deficient number, since it is larger than the sum of its proper divisors (7000013).

21000027 is an equidigital number, since it uses as much as digits as its factorization.

21000027 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7000012.

The product of its (nonzero) digits is 28, while the sum is 12.

The square root of 21000027 is about 4582.5786408964. The cubic root of 21000027 is about 275.8925358777.

Adding to 21000027 its reverse (72000012), we get a palindrome (93000039).

The spelling of 21000027 in words is "twenty-one million, twenty-seven", and thus it is an aban number and an uban number.