1661251521600 has 252 divisors, whose sum is σ = 6441251684400. Its totient is φ = 402727603200.

The previous prime is 1661251521581. The next prime is 1661251521613. The reversal of 1661251521600 is 61251521661.

1661251521600 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 25 + 1 + 5 + 21 + 600 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5085450 + ... + 5402249.

Almost surely, 2^{1661251521600} is an apocalyptic number.

1661251521600 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1661251521600 is an abundant number, since it is smaller than the sum of its proper divisors (4780000162800).

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

1661251521600 is a wasteful number, since it uses less digits than its factorization.

1661251521600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10487738 (or 10487720 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 1661251521600 in words is "one trillion, six hundred sixty-one billion, two hundred fifty-one million, five hundred twenty-one thousand, six hundred".