21206372 has 12 divisors (see below), whose sum is σ = 40484976. Its totient is φ = 9639240.

The previous prime is 21206363. The next prime is 21206377. The reversal of 21206372 is 27360212.

It is not an unprimeable number, because it can be changed into a prime (21206377) 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 3 ways as a sum of consecutive naturals, for example, 240938 + ... + 241025.

It is an arithmetic number, because the mean of its divisors is an integer number (3373748).

Almost surely, 2^21206372 is an apocalyptic number.

21206372 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21206372 is a deficient number, since it is larger than the sum of its proper divisors (19278604).

21206372 is a wasteful number, since it uses less digits than its factorization.

21206372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481978 (or 481976 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 21206372 is about 4605.0376762845. The cubic root of 21206372 is about 276.7932267212.

Adding to 21206372 its reverse (27360212), we get a palindrome (48566584).

The spelling of 21206372 in words is "twenty-one million, two hundred six thousand, three hundred seventy-two".