21630733 has 2 divisors, whose sum is σ = 21630734. Its totient is φ = 21630732.

The previous prime is 21630727. The next prime is 21630761. The reversal of 21630733 is 33703612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15856324 + 5774409 = 3982^2 + 2403^2 .

It is a cyclic number.

It is not a de Polignac number, because 21630733 - 2²¹ = 19533581 is a prime.

It is a super-2 number, since 2×21630733² = 935777220234578, which contains 22 as substring.

It is equal to p_1367341 and since 21630733 and 1367341 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 21630698 and 21630707.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21631733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10815366 + 10815367.

It is an arithmetic number, because the mean of its divisors is an integer number (10815367).

Almost surely, 2^21630733 is an apocalyptic number.

It is an amenable number.

21630733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21630733 is an equidigital number, since it uses as much as digits as its factorization.

21630733 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 25.

The square root of 21630733 is about 4650.8851845643. The cubic root of 21630733 is about 278.6273507092.

The spelling of 21630733 in words is "twenty-one million, six hundred thirty thousand, seven hundred thirty-three".