21206354 has 16 divisors (see below), whose sum is σ = 34728792. Its totient is φ = 9652608.

The previous prime is 21206347. The next prime is 21206357. The reversal of 21206354 is 45360212.

It can be written as a sum of positive squares in 4 ways, for example, as 15031129 + 6175225 = 3877^2 + 2485^2 .

It is not an unprimeable number, because it can be changed into a prime (21206357) 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 7 ways as a sum of consecutive naturals, for example, 3689 + ... + 7484.

Almost surely, 2^21206354 is an apocalyptic number.

21206354 is a deficient number, since it is larger than the sum of its proper divisors (13522438).

21206354 is a wasteful number, since it uses less digits than its factorization.

21206354 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11261.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21206354 is about 4605.0357219027. The cubic root of 21206354 is about 276.7931484070.

Adding to 21206354 its reverse (45360212), we get a palindrome (66566566).

The spelling of 21206354 in words is "twenty-one million, two hundred six thousand, three hundred fifty-four".