21033737 has 2 divisors, whose sum is σ = 21033738. Its totient is φ = 21033736.

The previous prime is 21033721. The next prime is 21033763. The reversal of 21033737 is 73733012.

It is a happy number.

It is an a-pointer prime, because the next prime (21033763) can be obtained adding 21033737 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18913801 + 2119936 = 4349^2 + 1456^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033737 - 2⁴ = 21033721 is a prime.

It is equal to p_1331972 and since 21033737 and 1331972 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21033767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516868 + 10516869.

It is an arithmetic number, because the mean of its divisors is an integer number (10516869).

Almost surely, 2^21033737 is an apocalyptic number.

It is an amenable number.

21033737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033737 is an equidigital number, since it uses as much as digits as its factorization.

21033737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2646, while the sum is 26.

The square root of 21033737 is about 4586.2552262167. The cubic root of 21033737 is about 276.0400811706.

Adding to 21033737 its reverse (73733012), we get a palindrome (94766749).

The spelling of 21033737 in words is "twenty-one million, thirty-three thousand, seven hundred thirty-seven".