7820400 has 240 divisors, whose sum is σ = 30752000. Its totient is φ = 1693440.

The previous prime is 7820399. The next prime is 7820411. The reversal of 7820400 is 40287.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×7820400² = 122317312320000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 411591 + ... + 411609.

Almost surely, 2^7820400 is an apocalyptic number.

7820400 is a gapful number since it is divisible by the number (70) 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 7820400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15376000).

7820400 is an abundant number, since it is smaller than the sum of its proper divisors (22931600).

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

7820400 is a wasteful number, since it uses less digits than its factorization.

7820400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 7820400 is about 2796.4978097613. The cubic root of 7820400 is about 198.4919914625.

Adding to 7820400 its reverse (40287), we get a palindrome (7860687).

The spelling of 7820400 in words is "seven million, eight hundred twenty thousand, four hundred".