21242629 has 2 divisors, whose sum is σ = 21242630. Its totient is φ = 21242628.

The previous prime is 21242591. The next prime is 21242651. The reversal of 21242629 is 92624212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12061729 + 9180900 = 3473^2 + 3030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242629 - 2²³ = 12854021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21242597 and 21242606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21242659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621314 + 10621315.

It is an arithmetic number, because the mean of its divisors is an integer number (10621315).

Almost surely, 2^21242629 is an apocalyptic number.

It is an amenable number.

21242629 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242629 is an equidigital number, since it uses as much as digits as its factorization.

21242629 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 28.

The square root of 21242629 is about 4608.9726621016. The cubic root of 21242629 is about 276.9508833921.

It can be divided in two parts, 2124 and 2629, that added together give a triangular number (4753 = T₉₇).

The spelling of 21242629 in words is "twenty-one million, two hundred forty-two thousand, six hundred twenty-nine".