31661261672400 has 480 divisors, whose sum is σ = 120230427081600. Its totient is φ = 7885690675200.

The previous prime is 31661261672389. The next prime is 31661261672479. The reversal of 31661261672400 is 427616216613.

31661261672400 is a `hidden beast` number, since 3 + 1 + 6 + 6 + 1 + 2 + 616 + 7 + 24 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 23393406 + ... + 24709794.

It is an arithmetic number, because the mean of its divisors is an integer number (250480056420).

Almost surely, 2^{31661261672400} is an apocalyptic number.

31661261672400 is a gapful number since it is divisible by the number (30) 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 31661261672400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60115213540800).

31661261672400 is an abundant number, since it is smaller than the sum of its proper divisors (88569165409200).

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

31661261672400 is a wasteful number, since it uses less digits than its factorization.

31661261672400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316564 (or 1316547 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The spelling of 31661261672400 in words is "thirty-one trillion, six hundred sixty-one billion, two hundred sixty-one million, six hundred seventy-two thousand, four hundred".