21840146 has 4 divisors (see below), whose sum is σ = 32760222. Its totient is φ = 10920072.

The previous prime is 21840131. The next prime is 21840149. The reversal of 21840146 is 64104812.

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., 14737921 + 7102225 = 3839^2 + 2665^2 .

It is not an unprimeable number, because it can be changed into a prime (21840149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5460035 + ... + 5460038.

Almost surely, 2^21840146 is an apocalyptic number.

21840146 is a deficient number, since it is larger than the sum of its proper divisors (10920076).

21840146 is a wasteful number, since it uses less digits than its factorization.

21840146 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10920075.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21840146 is about 4673.3441987510. The cubic root of 21840146 is about 279.5236202401.

Adding to 21840146 its reverse (64104812), we get a palindrome (85944958).

The spelling of 21840146 in words is "twenty-one million, eight hundred forty thousand, one hundred forty-six".