21400481 has 4 divisors (see below), whose sum is σ = 21413700. Its totient is φ = 21387264.

The previous prime is 21400459. The next prime is 21400487. The reversal of 21400481 is 18400412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8904256 + 12496225 = 2984^2 + 3535^2 .

It is a cyclic number.

It is not a de Polignac number, because 21400481 - 2⁶ = 21400417 is a prime.

It is a super-2 number, since 2×21400481² = 915961174062722, which contains 22 as substring.

It is a deceptive number, since it divides R_21400480.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21400487) 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 in 3 ways as a sum of consecutive naturals, for example, 3776 + ... + 7553.

It is an arithmetic number, because the mean of its divisors is an integer number (5353425).

It is a Poulet number, since it divides 2^21400480-1.

Almost surely, 2^21400481 is an apocalyptic number.

It is an amenable number.

21400481 is a deficient number, since it is larger than the sum of its proper divisors (13219).

21400481 is a wasteful number, since it uses less digits than its factorization.

21400481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13218.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21400481 is about 4626.0653908046. The cubic root of 21400481 is about 277.6351899250.

Adding to 21400481 its reverse (18400412), we get a palindrome (39800893).

The spelling of 21400481 in words is "twenty-one million, four hundred thousand, four hundred eighty-one".