1821516206400 has 1680 divisors, whose sum is σ = 7736240527488. Its totient is φ = 416047104000.

The previous prime is 1821516206369. The next prime is 1821516206407. The reversal of 1821516206400 is 46026151281.

It is a happy number.

1821516206400 is a `hidden beast` number, since 1 + 8 + 2 + 1 + 5 + 1 + 6 + 2 + 0 + 640 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821516206407) by changing a digit.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 2393582020 + ... + 2393582780.

Almost surely, 2^{1821516206400} is an apocalyptic number.

1821516206400 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 1821516206400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3868120263744).

1821516206400 is an abundant number, since it is smaller than the sum of its proper divisors (5914724321088).

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

1821516206400 is a wasteful number, since it uses less digits than its factorization.

1821516206400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902 (or 878 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 1821516206400 in words is "one trillion, eight hundred twenty-one billion, five hundred sixteen million, two hundred six thousand, four hundred".