21906037 has 2 divisors, whose sum is σ = 21906038. Its totient is φ = 21906036.

The previous prime is 21906019. The next prime is 21906041. The reversal of 21906037 is 73060912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21893041 + 12996 = 4679^2 + 114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21906037 - 2¹⁹ = 21381749 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21905996 and 21906014.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21906007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10953018 + 10953019.

It is an arithmetic number, because the mean of its divisors is an integer number (10953019).

Almost surely, 2^21906037 is an apocalyptic number.

It is an amenable number.

21906037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21906037 is an equidigital number, since it uses as much as digits as its factorization.

21906037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 21906037 is about 4680.3885522465. The cubic root of 21906037 is about 279.8044425323.

Adding to 21906037 its reverse (73060912), we get a palindrome (94966949).

The spelling of 21906037 in words is "twenty-one million, nine hundred six thousand, thirty-seven".