1261630001820 has 96 divisors (see below), whose sum is σ = 3687948859392. Its totient is φ = 321650357248.

The previous prime is 1261630001813. The next prime is 1261630001831. The reversal of 1261630001820 is 281000361621.

It is a super-2 number, since 2×1261630001820² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2625364 + ... + 3068516.

It is an arithmetic number, because the mean of its divisors is an integer number (38416133952).

Almost surely, 2^{1261630001820} is an apocalyptic number.

1261630001820 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 1261630001820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1843974429696).

1261630001820 is an abundant number, since it is smaller than the sum of its proper divisors (2426318857572).

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

1261630001820 is a wasteful number, since it uses less digits than its factorization.

1261630001820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445251 (or 445249 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The spelling of 1261630001820 in words is "one trillion, two hundred sixty-one billion, six hundred thirty million, one thousand, eight hundred twenty".