21767138 has 4 divisors (see below), whose sum is σ = 32650710. Its totient is φ = 10883568.

The previous prime is 21767099. The next prime is 21767147. The reversal of 21767138 is 83176712.

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., 17698849 + 4068289 = 4207^2 + 2017^2 .

It is a super-2 number, since 2×21767138² = 947616593422088, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21767098 and 21767107.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5441783 + ... + 5441786.

Almost surely, 2^21767138 is an apocalyptic number.

21767138 is a deficient number, since it is larger than the sum of its proper divisors (10883572).

21767138 is a wasteful number, since it uses less digits than its factorization.

21767138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10883571.

The product of its digits is 14112, while the sum is 35.

The square root of 21767138 is about 4665.5265512051. The cubic root of 21767138 is about 279.2118054384.

The spelling of 21767138 in words is "twenty-one million, seven hundred sixty-seven thousand, one hundred thirty-eight".