21656354 has 4 divisors (see below), whose sum is σ = 32484534. Its totient is φ = 10828176.

The previous prime is 21656353. The next prime is 21656357. The reversal of 21656354 is 45365612.

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

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 1630729 = 4475^2 + 1277^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21656354.

It is not an unprimeable number, because it can be changed into a prime (21656353) 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 as a sum of consecutive naturals, namely, 5414087 + ... + 5414090.

Almost surely, 2^21656354 is an apocalyptic number.

21656354 is a deficient number, since it is larger than the sum of its proper divisors (10828180).

21656354 is a wasteful number, since it uses less digits than its factorization.

21656354 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10828179.

The product of its digits is 21600, while the sum is 32.

The square root of 21656354 is about 4653.6387913116. The cubic root of 21656354 is about 278.7373160791.

The spelling of 21656354 in words is "twenty-one million, six hundred fifty-six thousand, three hundred fifty-four".