1321100020 has 24 divisors (see below), whose sum is σ = 2920327200. Its totient is φ = 500627232.

The previous prime is 1321100009. The next prime is 1321100041. The reversal of 1321100020 is 200011231.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1737910 + ... + 1738669.

It is an arithmetic number, because the mean of its divisors is an integer number (121680300).

Almost surely, 2^1321100020 is an apocalyptic number.

1321100020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1321100020 is an abundant number, since it is smaller than the sum of its proper divisors (1599227180).

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

1321100020 is a wasteful number, since it uses less digits than its factorization.

1321100020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3476607 (or 3476605 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 1321100020 is about 36346.9396235777. The cubic root of 1321100020 is about 1097.2659428959.

Adding to 1321100020 its reverse (200011231), we get a palindrome (1521111251).

The spelling of 1321100020 in words is "one billion, three hundred twenty-one million, one hundred thousand, twenty".