21475918 has 16 divisors (see below), whose sum is σ = 33230736. Its totient is φ = 10404160.

The previous prime is 21475907. The next prime is 21475939. The reversal of 21475918 is 81957412.

It is a super-2 number, since 2×21475918² = 922430107885448, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 7578 + ... + 10018.

It is an arithmetic number, because the mean of its divisors is an integer number (2076921).

Almost surely, 2^21475918 is an apocalyptic number.

21475918 is a deficient number, since it is larger than the sum of its proper divisors (11754818).

21475918 is a wasteful number, since it uses less digits than its factorization.

21475918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2579.

The product of its digits is 20160, while the sum is 37.

The square root of 21475918 is about 4634.2116913236. The cubic root of 21475918 is about 277.9610300256.

The spelling of 21475918 in words is "twenty-one million, four hundred seventy-five thousand, nine hundred eighteen".