1321728990 has 32 divisors (see below), whose sum is σ = 3176996256. Its totient is φ = 351922560.

The previous prime is 1321728979. The next prime is 1321728997. The reversal of 1321728990 is 998271231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321728997) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13497 + ... + 53156.

It is an arithmetic number, because the mean of its divisors is an integer number (99281133).

Almost surely, 2^1321728990 is an apocalyptic number.

1321728990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1321728990 is an abundant number, since it is smaller than the sum of its proper divisors (1855267266).

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

1321728990 is a wasteful number, since it uses less digits than its factorization.

1321728990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67324.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 1321728990 is about 36355.5909042887. The cubic root of 1321728990 is about 1097.4400497899.

The spelling of 1321728990 in words is "one billion, three hundred twenty-one million, seven hundred twenty-eight thousand, nine hundred ninety".