21620953 has 2 divisors, whose sum is σ = 21620954. Its totient is φ = 21620952.

The previous prime is 21620933. The next prime is 21620999. The reversal of 21620953 is 35902612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21557449 + 63504 = 4643^2 + 252^2 .

It is a cyclic number.

It is not a de Polignac number, because 21620953 - 2¹³ = 21612761 is a prime.

It is not a weakly prime, because it can be changed into another prime (21620903) 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, 10810476 + 10810477.

It is an arithmetic number, because the mean of its divisors is an integer number (10810477).

Almost surely, 2^21620953 is an apocalyptic number.

It is an amenable number.

21620953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620953 is an equidigital number, since it uses as much as digits as its factorization.

21620953 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 21620953 is about 4649.8336529386. The cubic root of 21620953 is about 278.5853520357.

The spelling of 21620953 in words is "twenty-one million, six hundred twenty thousand, nine hundred fifty-three".