21629437 has 2 divisors, whose sum is σ = 21629438. Its totient is φ = 21629436.

The previous prime is 21629417. The next prime is 21629471. The reversal of 21629437 is 73492612.

It is an a-pointer prime, because the next prime (21629471) can be obtained adding 21629437 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16088121 + 5541316 = 4011^2 + 2354^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21629437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21629417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10814718 + 10814719.

It is an arithmetic number, because the mean of its divisors is an integer number (10814719).

Almost surely, 2^21629437 is an apocalyptic number.

It is an amenable number.

21629437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21629437 is an equidigital number, since it uses as much as digits as its factorization.

21629437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 34.

The square root of 21629437 is about 4650.7458541615. The cubic root of 21629437 is about 278.6217859685.

The spelling of 21629437 in words is "twenty-one million, six hundred twenty-nine thousand, four hundred thirty-seven".