20921090 has 32 divisors (see below), whose sum is σ = 39960000. Its totient is φ = 7864128.

The previous prime is 20921083. The next prime is 20921119. The reversal of 20921090 is 9012902.

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 15 ways as a sum of consecutive naturals, for example, 27941 + ... + 28679.

It is an arithmetic number, because the mean of its divisors is an integer number (1248750).

Almost surely, 2^20921090 is an apocalyptic number.

20921090 is a deficient number, since it is larger than the sum of its proper divisors (19038910).

20921090 is a wasteful number, since it uses less digits than its factorization.

20921090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 914.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 20921090 is about 4573.9578047901. The cubic root of 20921090 is about 275.5464176957.

Adding to 20921090 its reverse (9012902), we get a palindrome (29933992).

The spelling of 20921090 in words is "twenty million, nine hundred twenty-one thousand, ninety".