21656146 has 4 divisors (see below), whose sum is σ = 32484222. Its totient is φ = 10828072.

The previous prime is 21656119. The next prime is 21656149. The reversal of 21656146 is 64165612.

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., 19900521 + 1755625 = 4461^2 + 1325^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21656149) 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, 5414035 + ... + 5414038.

Almost surely, 2^21656146 is an apocalyptic number.

21656146 is a deficient number, since it is larger than the sum of its proper divisors (10828076).

21656146 is a wasteful number, since it uses less digits than its factorization.

21656146 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10828075.

The product of its digits is 8640, while the sum is 31.

The square root of 21656146 is about 4653.6164431547. The cubic root of 21656146 is about 278.7364236921.

The spelling of 21656146 in words is "twenty-one million, six hundred fifty-six thousand, one hundred forty-six".