21791137 has 2 divisors, whose sum is σ = 21791138. Its totient is φ = 21791136.

The previous prime is 21791117. The next prime is 21791149. The reversal of 21791137 is 73119712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12845056 + 8946081 = 3584^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 21791137 - 2¹⁹ = 21266849 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21791099 and 21791108.

It is not a weakly prime, because it can be changed into another prime (21791117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10895568 + 10895569.

It is an arithmetic number, because the mean of its divisors is an integer number (10895569).

Almost surely, 2^21791137 is an apocalyptic number.

It is an amenable number.

21791137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21791137 is an equidigital number, since it uses as much as digits as its factorization.

21791137 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2646, while the sum is 31.

The square root of 21791137 is about 4668.0977924632. The cubic root of 21791137 is about 279.3143812112.

The spelling of 21791137 in words is "twenty-one million, seven hundred ninety-one thousand, one hundred thirty-seven".