21781474 has 16 divisors (see below), whose sum is σ = 38384640. Its totient is φ = 9138960.

The previous prime is 21781469. The next prime is 21781477. The reversal of 21781474 is 47418712.

It is a super-2 number, since 2×21781474² = 948865219225352, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21781477) 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, 37794 + ... + 38365.

It is an arithmetic number, because the mean of its divisors is an integer number (2399040).

Almost surely, 2^21781474 is an apocalyptic number.

21781474 is a deficient number, since it is larger than the sum of its proper divisors (16603166).

21781474 is a wasteful number, since it uses less digits than its factorization.

21781474 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76185.

The product of its digits is 12544, while the sum is 34.

The square root of 21781474 is about 4667.0626736739. The cubic root of 21781474 is about 279.2730889813.

The spelling of 21781474 in words is "twenty-one million, seven hundred eighty-one thousand, four hundred seventy-four".