21335137 has 2 divisors, whose sum is σ = 21335138. Its totient is φ = 21335136.

The previous prime is 21335123. The next prime is 21335141. The reversal of 21335137 is 73153312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12988816 + 8346321 = 3604^2 + 2889^2 .

It is a cyclic number.

It is not a de Polignac number, because 21335137 - 2¹¹ = 21333089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21335107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10667568 + 10667569.

It is an arithmetic number, because the mean of its divisors is an integer number (10667569).

Almost surely, 2^21335137 is an apocalyptic number.

It is an amenable number.

21335137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21335137 is an equidigital number, since it uses as much as digits as its factorization.

21335137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1890, while the sum is 25.

The square root of 21335137 is about 4618.9974020343. The cubic root of 21335137 is about 277.3523257239.

Adding to 21335137 its reverse (73153312), we get a palindrome (94488449).

It can be divided in two parts, 213351 and 37, that multiplied together give a palindrome (7893987).

The spelling of 21335137 in words is "twenty-one million, three hundred thirty-five thousand, one hundred thirty-seven".