21147157 has 2 divisors, whose sum is σ = 21147158. Its totient is φ = 21147156.

The previous prime is 21147127. The next prime is 21147163. The reversal of 21147157 is 75174112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14791716 + 6355441 = 3846^2 + 2521^2 .

It is a cyclic number.

It is not a de Polignac number, because 21147157 - 2⁷ = 21147029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21147107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573578 + 10573579.

It is an arithmetic number, because the mean of its divisors is an integer number (10573579).

Almost surely, 2^21147157 is an apocalyptic number.

It is an amenable number.

21147157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21147157 is an equidigital number, since it uses as much as digits as its factorization.

21147157 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1960, while the sum is 28.

The square root of 21147157 is about 4598.6038098536. The cubic root of 21147157 is about 276.5353546958.

The spelling of 21147157 in words is "twenty-one million, one hundred forty-seven thousand, one hundred fifty-seven".