21481678 has 16 divisors (see below), whose sum is σ = 33729696. Its totient is φ = 10241440.

The previous prime is 21481673. The next prime is 21481687. The reversal of 21481678 is 87618412.

It is a super-2 number, since 2×21481678² = 922924979391368, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481673) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 20700 + ... + 21712.

It is an arithmetic number, because the mean of its divisors is an integer number (2108106).

Almost surely, 2^21481678 is an apocalyptic number.

21481678 is a deficient number, since it is larger than the sum of its proper divisors (12248018).

21481678 is a wasteful number, since it uses less digits than its factorization.

21481678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1499.

The product of its digits is 21504, while the sum is 37.

The square root of 21481678 is about 4634.8331145792. The cubic root of 21481678 is about 277.9858782054.

The spelling of 21481678 in words is "twenty-one million, four hundred eighty-one thousand, six hundred seventy-eight".