20401920 has 432 divisors, whose sum is σ = 91832832. Its totient is φ = 4055040.

The previous prime is 20401919. The next prime is 20401933. The reversal of 20401920 is 2910402.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20401893 and 20401902.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 887029 + ... + 887051.

It is an arithmetic number, because the mean of its divisors is an integer number (212576).

Almost surely, 2^20401920 is an apocalyptic number.

20401920 is a gapful number since it is divisible by the number (20) 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 20401920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45916416).

20401920 is an abundant number, since it is smaller than the sum of its proper divisors (71430912).

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

20401920 is a wasteful number, since it uses less digits than its factorization.

20401920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 51 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 20401920 is about 4516.8484588261. The cubic root of 20401920 is about 273.2480135583.

It can be divided in two parts, 20401 and 920, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 20401920 in words is "twenty million, four hundred one thousand, nine hundred twenty".