21453405 has 16 divisors (see below), whose sum is σ = 36345024. Its totient is φ = 10768640.

The previous prime is 21453401. The next prime is 21453427. The reversal of 21453405 is 50435412.

It is not a de Polignac number, because 21453405 - 2² = 21453401 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21453401) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41811 + ... + 42320.

It is an arithmetic number, because the mean of its divisors is an integer number (2271564).

Almost surely, 2^21453405 is an apocalyptic number.

It is an amenable number.

21453405 is a deficient number, since it is larger than the sum of its proper divisors (14891619).

21453405 is a wasteful number, since it uses less digits than its factorization.

21453405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84156.

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 21453405 is about 4631.7820544581. The cubic root of 21453405 is about 277.8638681009.

Adding to 21453405 its reverse (50435412), we get a palindrome (71888817).

The spelling of 21453405 in words is "twenty-one million, four hundred fifty-three thousand, four hundred five".