20855421 has 16 divisors (see below), whose sum is σ = 31124800. Its totient is φ = 13801104.

The previous prime is 20855377. The next prime is 20855423. The reversal of 20855421 is 12455802.

It is a happy number.

It is not a de Polignac number, because 20855421 - 2¹⁰ = 20854397 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20855423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 975 + ... + 6531.

It is an arithmetic number, because the mean of its divisors is an integer number (1945300).

Almost surely, 2^20855421 is an apocalyptic number.

It is an amenable number.

20855421 is a deficient number, since it is larger than the sum of its proper divisors (10269379).

20855421 is a wasteful number, since it uses less digits than its factorization.

20855421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5705 (or 5699 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 20855421 is about 4566.7735875561. The cubic root of 20855421 is about 275.2578122203.

The spelling of 20855421 in words is "twenty million, eight hundred fifty-five thousand, four hundred twenty-one".