21153481 has 2 divisors, whose sum is σ = 21153482. Its totient is φ = 21153480.

The previous prime is 21153443. The next prime is 21153493. The reversal of 21153481 is 18435112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12362256 + 8791225 = 3516^2 + 2965^2 .

It is a cyclic number.

It is not a de Polignac number, because 21153481 - 2⁹ = 21152969 is a prime.

It is a super-2 number, since 2×21153481² = 894939516834722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21153281) 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, 10576740 + 10576741.

It is an arithmetic number, because the mean of its divisors is an integer number (10576741).

Almost surely, 2^21153481 is an apocalyptic number.

It is an amenable number.

21153481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21153481 is an equidigital number, since it uses as much as digits as its factorization.

21153481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 25.

The square root of 21153481 is about 4599.2913584595. The cubic root of 21153481 is about 276.5629176646.

Adding to 21153481 its reverse (18435112), we get a palindrome (39588593).

The spelling of 21153481 in words is "twenty-one million, one hundred fifty-three thousand, four hundred eighty-one".