400221820 has 48 divisors (see below), whose sum is σ = 903238560. Its totient is φ = 148414464.

The previous prime is 400221751. The next prime is 400221889. The reversal of 400221820 is 28122004.

It is an interprime number because it is at equal distance from previous prime (400221751) and next prime (400221889).

It is a super-2 number, since 2×400221820² = 320355010408224800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13996 + ... + 31564.

It is an arithmetic number, because the mean of its divisors is an integer number (18817470).

Almost surely, 2^400221820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400221820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (451619280).

400221820 is an abundant number, since it is smaller than the sum of its proper divisors (503016740).

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

400221820 is a wasteful number, since it uses less digits than its factorization.

400221820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17662 (or 17660 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 400221820 is about 20005.5447313988. The cubic root of 400221820 is about 736.9424732040.

Adding to 400221820 its reverse (28122004), we get a palindrome (428343824).

The spelling of 400221820 in words is "four hundred million, two hundred twenty-one thousand, eight hundred twenty".