20921472 has 192 divisors, whose sum is σ = 71285760. Its totient is φ = 5806080.

The previous prime is 20921449. The next prime is 20921479. The reversal of 20921472 is 27412902.

It is a tau number, because it is divible by the number of its divisors (192).

It is not an unprimeable number, because it can be changed into a prime (20921479) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 164673 + ... + 164799.

It is an arithmetic number, because the mean of its divisors is an integer number (371280).

Almost surely, 2^20921472 is an apocalyptic number.

20921472 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20921472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35642880).

20921472 is an abundant number, since it is smaller than the sum of its proper divisors (50364288).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20921472 is a wasteful number, since it uses less digits than its factorization.

20921472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 156 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 20921472 is about 4573.9995627459. Note that the first 3 decimals coincide. The cubic root of 20921472 is about 275.5480947608.

The spelling of 20921472 in words is "twenty million, nine hundred twenty-one thousand, four hundred seventy-two".