21012151 has 2 divisors, whose sum is σ = 21012152. Its totient is φ = 21012150.

The previous prime is 21012137. The next prime is 21012161. The reversal of 21012151 is 15121012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012161) 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, 10506075 + 10506076.

It is an arithmetic number, because the mean of its divisors is an integer number (10506076).

Almost surely, 2^21012151 is an apocalyptic number.

21012151 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012151 is an equidigital number, since it uses as much as digits as its factorization.

21012151 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20, while the sum is 13.

The square root of 21012151 is about 4583.9012860226. The cubic root of 21012151 is about 275.9456195809.

Adding to 21012151 its reverse (15121012), we get a palindrome (36133163).

The spelling of 21012151 in words is "twenty-one million, twelve thousand, one hundred fifty-one".