21988774 has 8 divisors (see below), whose sum is σ = 33224328. Its totient is φ = 10914000.

The previous prime is 21988763. The next prime is 21988777. The reversal of 21988774 is 47788912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21988777) 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 3 ways as a sum of consecutive naturals, for example, 39852 + ... + 40399.

It is an arithmetic number, because the mean of its divisors is an integer number (4153041).

Almost surely, 2^21988774 is an apocalyptic number.

21988774 is a deficient number, since it is larger than the sum of its proper divisors (11235554).

21988774 is a wasteful number, since it uses less digits than its factorization.

21988774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80390.

The product of its digits is 225792, while the sum is 46.

The square root of 21988774 is about 4689.2189115033. The cubic root of 21988774 is about 280.1562648150.

It can be divided in two parts, 219887 and 74, that added together give a square (219961 = 469²).

The spelling of 21988774 in words is "twenty-one million, nine hundred eighty-eight thousand, seven hundred seventy-four".