21421090 has 32 divisors (see below), whose sum is σ = 39481344. Its totient is φ = 8366400.

The previous prime is 21421061. The next prime is 21421091. The reversal of 21421090 is 9012412.

It is not an unprimeable number, because it can be changed into a prime (21421091) 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 15 ways as a sum of consecutive naturals, for example, 128187 + ... + 128353.

It is an arithmetic number, because the mean of its divisors is an integer number (1233792).

Almost surely, 2^21421090 is an apocalyptic number.

21421090 is a deficient number, since it is larger than the sum of its proper divisors (18060254).

21421090 is a wasteful number, since it uses less digits than its factorization.

21421090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21421090 is about 4628.2923416742. The cubic root of 21421090 is about 277.7242836840.

The spelling of 21421090 in words is "twenty-one million, four hundred twenty-one thousand, ninety".