21746945 has 16 divisors (see below), whose sum is σ = 28874880. Its totient is φ = 15590400.

The previous prime is 21746941. The next prime is 21746957. The reversal of 21746945 is 54964712.

It is not a de Polignac number, because 21746945 - 2² = 21746941 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21746899 and 21746908.

It is not an unprimeable number, because it can be changed into a prime (21746941) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 1121 + ... + 6689.

It is an arithmetic number, because the mean of its divisors is an integer number (1804680).

Almost surely, 2^21746945 is an apocalyptic number.

It is an amenable number.

21746945 is a deficient number, since it is larger than the sum of its proper divisors (7127935).

21746945 is a wasteful number, since it uses less digits than its factorization.

21746945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5656.

The product of its digits is 60480, while the sum is 38.

The square root of 21746945 is about 4663.3619846630. The cubic root of 21746945 is about 279.1254387274.

It can be divided in two parts, 2174 and 6945, that added together give a palindrome (9119).

The spelling of 21746945 in words is "twenty-one million, seven hundred forty-six thousand, nine hundred forty-five".