21406153 has 2 divisors, whose sum is σ = 21406154. Its totient is φ = 21406152.

The previous prime is 21406109. The next prime is 21406157. The reversal of 21406153 is 35160412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21049744 + 356409 = 4588^2 + 597^2 .

It is a cyclic number.

It is not a de Polignac number, because 21406153 - 2⁹ = 21405641 is a prime.

It is not a weakly prime, because it can be changed into another prime (21406157) 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, 10703076 + 10703077.

It is an arithmetic number, because the mean of its divisors is an integer number (10703077).

Almost surely, 2^21406153 is an apocalyptic number.

It is an amenable number.

21406153 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406153 is an equidigital number, since it uses as much as digits as its factorization.

21406153 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21406153 is about 4626.6783981600. The cubic root of 21406153 is about 277.6597159734.

Adding to 21406153 its reverse (35160412), we get a palindrome (56566565).

The spelling of 21406153 in words is "twenty-one million, four hundred six thousand, one hundred fifty-three".