20213820 has 192 divisors, whose sum is σ = 71124480. Its totient is φ = 4723200.

The previous prime is 20213819. The next prime is 20213857. The reversal of 20213820 is 2831202.

20213820 = T₆₅₆ + T₆₅₇ + ... + T₇₃₈.

It is a happy number.

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 = 20213793 and 20213802.

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 63 ways as a sum of consecutive naturals, for example, 243499 + ... + 243581.

It is an arithmetic number, because the mean of its divisors is an integer number (370440).

Almost surely, 2^20213820 is an apocalyptic number.

20213820 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 20213820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35562240).

20213820 is an abundant number, since it is smaller than the sum of its proper divisors (50910660).

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

20213820 is a wasteful number, since it uses less digits than its factorization.

20213820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153 (or 145 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 20213820 is about 4495.9782027941. The cubic root of 20213820 is about 272.4056627129.

The spelling of 20213820 in words is "twenty million, two hundred thirteen thousand, eight hundred twenty".