21147937 has 2 divisors, whose sum is σ = 21147938. Its totient is φ = 21147936.

The previous prime is 21147869. The next prime is 21147941. The reversal of 21147937 is 73974112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13133376 + 8014561 = 3624^2 + 2831^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21147937 is a prime.

It is not a weakly prime, because it can be changed into another prime (21147967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573968 + 10573969.

It is an arithmetic number, because the mean of its divisors is an integer number (10573969).

Almost surely, 2^21147937 is an apocalyptic number.

It is an amenable number.

21147937 is a deficient number, since it is larger than the sum of its proper divisors (1).

21147937 is an equidigital number, since it uses as much as digits as its factorization.

21147937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 34.

The square root of 21147937 is about 4598.6886174213. The cubic root of 21147937 is about 276.5387546000.

The spelling of 21147937 in words is "twenty-one million, one hundred forty-seven thousand, nine hundred thirty-seven".