21481653 has 4 divisors (see below), whose sum is σ = 28642208. Its totient is φ = 14321100.

The previous prime is 21481651. The next prime is 21481657. The reversal of 21481653 is 35618412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21481653 - 2¹ = 21481651 is a prime.

It is a super-2 number, since 2×21481653² = 922922831224818, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21481653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481651) 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 in 3 ways as a sum of consecutive naturals, for example, 3580273 + ... + 3580278.

It is an arithmetic number, because the mean of its divisors is an integer number (7160552).

Almost surely, 2^21481653 is an apocalyptic number.

It is an amenable number.

21481653 is a deficient number, since it is larger than the sum of its proper divisors (7160555).

21481653 is an equidigital number, since it uses as much as digits as its factorization.

21481653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7160554.

The product of its digits is 5760, while the sum is 30.

The square root of 21481653 is about 4634.8304176097. The cubic root of 21481653 is about 277.9857703670.

The spelling of 21481653 in words is "twenty-one million, four hundred eighty-one thousand, six hundred fifty-three".