21878546 has 4 divisors (see below), whose sum is σ = 32817822. Its totient is φ = 10939272.

The previous prime is 21878531. The next prime is 21878567. The reversal of 21878546 is 64587812.

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., 14100025 + 7778521 = 3755^2 + 2789^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5469635 + ... + 5469638.

Almost surely, 2^21878546 is an apocalyptic number.

21878546 is a deficient number, since it is larger than the sum of its proper divisors (10939276).

21878546 is a wasteful number, since it uses less digits than its factorization.

21878546 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10939275.

The product of its digits is 107520, while the sum is 41.

The square root of 21878546 is about 4677.4508014516. The cubic root of 21878546 is about 279.6873465933.

The spelling of 21878546 in words is "twenty-one million, eight hundred seventy-eight thousand, five hundred forty-six".