21454405 has 24 divisors (see below), whose sum is σ = 30418848. Its totient is φ = 14480928.

The previous prime is 21454397. The next prime is 21454409. The reversal of 21454405 is 50445412.

It is a happy number.

It is not a de Polignac number, because 21454405 - 2³ = 21454397 is a prime.

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 21454405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21454409) 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 23 ways as a sum of consecutive naturals, for example, 15762 + ... + 17068.

It is an arithmetic number, because the mean of its divisors is an integer number (1267452).

Almost surely, 2^21454405 is an apocalyptic number.

It is an amenable number.

21454405 is a deficient number, since it is larger than the sum of its proper divisors (8964443).

21454405 is a wasteful number, since it uses less digits than its factorization.

21454405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1393 (or 1386 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

The square root of 21454405 is about 4631.8900030117. The cubic root of 21454405 is about 277.8681853573.

Adding to 21454405 its reverse (50445412), we get a palindrome (71899817).

The spelling of 21454405 in words is "twenty-one million, four hundred fifty-four thousand, four hundred five".