1988433721 has 2 divisors, whose sum is σ = 1988433722. Its totient is φ = 1988433720.

The previous prime is 1988433709. The next prime is 1988433773. The reversal of 1988433721 is 1273348891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1974558096 + 13875625 = 44436^2 + 3725^2 .

It is a cyclic number.

It is not a de Polignac number, because 1988433721 - 2⁷ = 1988433593 is a prime.

It is not a weakly prime, because it can be changed into another prime (1988433221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 994216860 + 994216861.

It is an arithmetic number, because the mean of its divisors is an integer number (994216861).

Almost surely, 2^1988433721 is an apocalyptic number.

It is an amenable number.

1988433721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1988433721 is an equidigital number, since it uses as much as digits as its factorization.

1988433721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 46.

The square root of 1988433721 is about 44591.8571153972. The cubic root of 1988433721 is about 1257.4875864324.

The spelling of 1988433721 in words is "one billion, nine hundred eighty-eight million, four hundred thirty-three thousand, seven hundred twenty-one".