16561144400 has 60 divisors (see below), whose sum is σ = 40140366492. Its totient is φ = 6565816320.

The previous prime is 16561144367. The next prime is 16561144433. The reversal of 16561144400 is 444116561.

It is an interprime number because it is at equal distance from previous prime (16561144367) and next prime (16561144433).

It can be written as a sum of positive squares in 6 ways, for example, as 6873073216 + 9688071184 = 82904^2 + 98428^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 137999 + ... + 228398.

Almost surely, 2^16561144400 is an apocalyptic number.

16561144400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16561144400 is an abundant number, since it is smaller than the sum of its proper divisors (23579222092).

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

16561144400 is a wasteful number, since it uses less digits than its factorization.

16561144400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366528 (or 366517 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 32.

The spelling of 16561144400 in words is "sixteen billion, five hundred sixty-one million, one hundred forty-four thousand, four hundred".