1261211400 has 72 divisors (see below), whose sum is σ = 4235574330. Its totient is φ = 336322560.

The previous prime is 1261211381. The next prime is 1261211401. The reversal of 1261211400 is 41121621.

1261211400 is a `hidden beast` number, since 1 + 2 + 612 + 11 + 40 + 0 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 1004763204 + 256448196 = 31698^2 + 16014^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261211401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 348537 + ... + 352136.

Almost surely, 2^1261211400 is an apocalyptic number.

1261211400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261211400 is an abundant number, since it is smaller than the sum of its proper divisors (2974362930).

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

1261211400 is a wasteful number, since it uses less digits than its factorization.

1261211400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 700695 (or 700683 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 1261211400 is about 35513.5382635974. The cubic root of 1261211400 is about 1080.4283280450.

The spelling of 1261211400 in words is "one billion, two hundred sixty-one million, two hundred eleven thousand, four hundred".