21775438 has 4 divisors (see below), whose sum is σ = 32663160. Its totient is φ = 10887718.

The previous prime is 21775427. The next prime is 21775441. The reversal of 21775438 is 83457712.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21775397 and 21775406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5443858 + ... + 5443861.

It is an arithmetic number, because the mean of its divisors is an integer number (8165790).

Almost surely, 2^21775438 is an apocalyptic number.

21775438 is a deficient number, since it is larger than the sum of its proper divisors (10887722).

21775438 is a wasteful number, since it uses less digits than its factorization.

21775438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10887721.

The product of its digits is 47040, while the sum is 37.

The square root of 21775438 is about 4666.4159694566. The cubic root of 21775438 is about 279.2472895627.

The spelling of 21775438 in words is "twenty-one million, seven hundred seventy-five thousand, four hundred thirty-eight".