1261949216400 has 90 divisors (see below), whose sum is σ = 4379314334850. Its totient is φ = 336519790080.

The previous prime is 1261949216357. The next prime is 1261949216401. The reversal of 1261949216400 is 46129491621.

1261949216400 is a `hidden beast` number, since 1 + 2 + 61 + 94 + 92 + 16 + 400 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 18849093264 + 1243100123136 = 137292^2 + 1114944^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (1261949216401) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 175267125 + ... + 175274324.

It is an arithmetic number, because the mean of its divisors is an integer number (48659048165).

Almost surely, 2^{1261949216400} is an apocalyptic number.

1261949216400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261949216400 is an abundant number, since it is smaller than the sum of its proper divisors (3117365118450).

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

1261949216400 is a wasteful number, since it uses less digits than its factorization.

1261949216400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350541473 (or 350541459 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 1261949216400 in words is "one trillion, two hundred sixty-one billion, nine hundred forty-nine million, two hundred sixteen thousand, four hundred".