21012127 has 2 divisors, whose sum is σ = 21012128. Its totient is φ = 21012126.

The previous prime is 21012091. The next prime is 21012137. The reversal of 21012127 is 72121012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21012127 - 2¹⁵ = 20979359 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21012127.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012137) 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, 10506063 + 10506064.

It is an arithmetic number, because the mean of its divisors is an integer number (10506064).

Almost surely, 2^21012127 is an apocalyptic number.

21012127 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012127 is an equidigital number, since it uses as much as digits as its factorization.

21012127 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 21012127 is about 4583.8986681645. The cubic root of 21012127 is about 275.9455145195.

Adding to 21012127 its reverse (72121012), we get a palindrome (93133139).

The spelling of 21012127 in words is "twenty-one million, twelve thousand, one hundred twenty-seven".