21660151 has 2 divisors, whose sum is σ = 21660152. Its totient is φ = 21660150.

The previous prime is 21660137. The next prime is 21660161. The reversal of 21660151 is 15106612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21660151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21660101) 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, 10830075 + 10830076.

It is an arithmetic number, because the mean of its divisors is an integer number (10830076).

Almost surely, 2^21660151 is an apocalyptic number.

21660151 is a deficient number, since it is larger than the sum of its proper divisors (1).

21660151 is an equidigital number, since it uses as much as digits as its factorization.

21660151 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21660151 is about 4654.0467337576. The cubic root of 21660151 is about 278.7536054284.

Adding to 21660151 its reverse (15106612), we get a palindrome (36766763).

The spelling of 21660151 in words is "twenty-one million, six hundred sixty thousand, one hundred fifty-one".