642951989 has 2 divisors, whose sum is σ = 642951990. Its totient is φ = 642951988.

The previous prime is 642951983. The next prime is 642952027. The reversal of 642951989 is 989159246.

642951989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 573363025 + 69588964 = 23945^2 + 8342^2 .

It is a cyclic number.

It is not a de Polignac number, because 642951989 - 2⁴ = 642951973 is a prime.

It is a super-2 number, since 2×642951989² = 826774520318112242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 642951989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642951983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321475994 + 321475995.

It is an arithmetic number, because the mean of its divisors is an integer number (321475995).

Almost surely, 2^642951989 is an apocalyptic number.

It is an amenable number.

642951989 is a deficient number, since it is larger than the sum of its proper divisors (1).

642951989 is an equidigital number, since it uses as much as digits as its factorization.

642951989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1399680, while the sum is 53.

The square root of 642951989 is about 25356.4979640328. The cubic root of 642951989 is about 863.0968164766.

The spelling of 642951989 in words is "six hundred forty-two million, nine hundred fifty-one thousand, nine hundred eighty-nine".