1261990125 has 112 divisors (see below), whose sum is σ = 2578080960. Its totient is φ = 611388000.

The previous prime is 1261990123. The next prime is 1261990133. The reversal of 1261990125 is 5210991621.

1261990125 is a `hidden beast` number, since 12 + 619 + 9 + 0 + 1 + 25 = 666.

It is not a de Polignac number, because 1261990125 - 2¹ = 1261990123 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1261990125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261990123) by changing a digit.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 1001746 + ... + 1003004.

It is an arithmetic number, because the mean of its divisors is an integer number (23018580).

Almost surely, 2^1261990125 is an apocalyptic number.

1261990125 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261990125 is an abundant number, since it is smaller than the sum of its proper divisors (1316090835).

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

1261990125 is an equidigital number, since it uses as much as digits as its factorization.

1261990125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1303 (or 1278 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 1261990125 is about 35524.5003483511. The cubic root of 1261990125 is about 1080.6506496019.

The spelling of 1261990125 in words is "one billion, two hundred sixty-one million, nine hundred ninety thousand, one hundred twenty-five".