21906028 has 12 divisors (see below), whose sum is σ = 40002480. Its totient is φ = 10476752.

The previous prime is 21906019. The next prime is 21906037. The reversal of 21906028 is 82060912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21906019) and next prime (21906037).

It is a junction number, because it is equal to n+sod(n) for n = 21905987 and 21906005.

It is an unprimeable number.

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, 118963 + ... + 119146.

It is an arithmetic number, because the mean of its divisors is an integer number (3333540).

Almost surely, 2^21906028 is an apocalyptic number.

It is an amenable number.

21906028 is a deficient number, since it is larger than the sum of its proper divisors (18096452).

21906028 is a wasteful number, since it uses less digits than its factorization.

21906028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238136 (or 238134 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21906028 is about 4680.3875907878. The cubic root of 21906028 is about 279.8044042135.

The spelling of 21906028 in words is "twenty-one million, nine hundred six thousand, twenty-eight".