1820400 has 120 divisors (see below), whose sum is σ = 6135024. Its totient is φ = 460800.

The previous prime is 1820389. The next prime is 1820407. The reversal of 1820400 is 40281.

1820400 = T₄₆₉ + T₄₇₀ + ... + T₄₈₄.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 1820400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820407) 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, 44380 + ... + 44420.

2^1820400 is an apocalyptic number.

1820400 is a gapful number since it is divisible by the number (10) 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 1820400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3067512).

1820400 is an abundant number, since it is smaller than the sum of its proper divisors (4314624).

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

1820400 is a wasteful number, since it uses less digits than its factorization.

1820400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 88 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 1820400 is about 1349.2219980418. The cubic root of 1820400 is about 122.1018588554.

Adding to 1820400 its reverse (40281), we get a palindrome (1860681).

The spelling of 1820400 in words is "one million, eight hundred twenty thousand, four hundred".