1261405600 has 144 divisors (see below), whose sum is σ = 3790257408. Its totient is φ = 399191040.

The previous prime is 1261405567. The next prime is 1261405603. The reversal of 1261405600 is 65041621.

It is a super-2 number, since 2×1261405600² = 3182288175422720000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261405603) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 64137 + ... + 81463.

It is an arithmetic number, because the mean of its divisors is an integer number (26321232).

Almost surely, 2^1261405600 is an apocalyptic number.

1261405600 is a gapful number since it is divisible by the number (10) 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 1261405600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1895128704).

1261405600 is an abundant number, since it is smaller than the sum of its proper divisors (2528851808).

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

1261405600 is a wasteful number, since it uses less digits than its factorization.

1261405600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17367 (or 17354 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 1261405600 is about 35516.2723269208. The cubic root of 1261405600 is about 1080.4837796035.

The spelling of 1261405600 in words is "one billion, two hundred sixty-one million, four hundred five thousand, six hundred".