21099406 has 16 divisors (see below), whose sum is σ = 33291648. Its totient is φ = 10015200.

The previous prime is 21099391. The next prime is 21099413. The reversal of 21099406 is 60499012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (31).

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, 76 + ... + 6496.

It is an arithmetic number, because the mean of its divisors is an integer number (2080728).

Almost surely, 2^21099406 is an apocalyptic number.

21099406 is a deficient number, since it is larger than the sum of its proper divisors (12192242).

21099406 is a wasteful number, since it uses less digits than its factorization.

21099406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6507.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 21099406 is about 4593.4089737362. The cubic root of 21099406 is about 276.3270557551.

The spelling of 21099406 in words is "twenty-one million, ninety-nine thousand, four hundred six".