21638153 has 2 divisors, whose sum is σ = 21638154. Its totient is φ = 21638152.

The previous prime is 21638143. The next prime is 21638167. The reversal of 21638153 is 35183612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17749369 + 3888784 = 4213^2 + 1972^2 .

It is a cyclic number.

It is not a de Polignac number, because 21638153 - 2¹⁸ = 21376009 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21638143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10819076 + 10819077.

It is an arithmetic number, because the mean of its divisors is an integer number (10819077).

Almost surely, 2^21638153 is an apocalyptic number.

It is an amenable number.

21638153 is a deficient number, since it is larger than the sum of its proper divisors (1).

21638153 is an equidigital number, since it uses as much as digits as its factorization.

21638153 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 29.

The square root of 21638153 is about 4651.6828137783. The cubic root of 21638153 is about 278.6592062885.

The spelling of 21638153 in words is "twenty-one million, six hundred thirty-eight thousand, one hundred fifty-three".