21929746 has 4 divisors (see below), whose sum is σ = 32894622. Its totient is φ = 10964872.

The previous prime is 21929723. The next prime is 21929749. The reversal of 21929746 is 64792912.

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., 17682025 + 4247721 = 4205^2 + 2061^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 21929699 and 21929708.

It is not an unprimeable number, because it can be changed into a prime (21929749) 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 as a sum of consecutive naturals, namely, 5482435 + ... + 5482438.

Almost surely, 2^21929746 is an apocalyptic number.

21929746 is a deficient number, since it is larger than the sum of its proper divisors (10964876).

21929746 is a wasteful number, since it uses less digits than its factorization.

21929746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10964875.

The product of its digits is 54432, while the sum is 40.

The square root of 21929746 is about 4682.9206698384. The cubic root of 21929746 is about 279.9053506620.

The spelling of 21929746 in words is "twenty-one million, nine hundred twenty-nine thousand, seven hundred forty-six".