21205454 has 8 divisors (see below), whose sum is σ = 31828080. Its totient is φ = 10596096.

The previous prime is 21205453. The next prime is 21205523. The reversal of 21205454 is 45450212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21205454² = 899342558692232, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205453) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3407 + ... + 7349.

It is an arithmetic number, because the mean of its divisors is an integer number (3978510).

Almost surely, 2^21205454 is an apocalyptic number.

21205454 is a deficient number, since it is larger than the sum of its proper divisors (10622626).

21205454 is a wasteful number, since it uses less digits than its factorization.

21205454 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6634.

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 21205454 is about 4604.9380017542. The cubic root of 21205454 is about 276.7892326411.

Adding to 21205454 its reverse (45450212), we get a palindrome (66655666).

The spelling of 21205454 in words is "twenty-one million, two hundred five thousand, four hundred fifty-four".