642249909 has 72 divisors (see below), whose sum is σ = 1126794240. Its totient is φ = 351086400.

The previous prime is 642249857. The next prime is 642249911. The reversal of 642249909 is 909942246.

It is a happy number.

It is not a de Polignac number, because 642249909 - 2⁷ = 642249781 is a prime.

It is a super-2 number, since 2×642249909² = 824969891221016562, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642249929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1489924 + ... + 1490354.

It is an arithmetic number, because the mean of its divisors is an integer number (15649920).

Almost surely, 2^642249909 is an apocalyptic number.

It is an amenable number.

642249909 is a deficient number, since it is larger than the sum of its proper divisors (484544331).

642249909 is a wasteful number, since it uses less digits than its factorization.

642249909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 591 (or 581 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The square root of 642249909 is about 25342.6499995561. The cubic root of 642249909 is about 862.7825453644.

The spelling of 642249909 in words is "six hundred forty-two million, two hundred forty-nine thousand, nine hundred nine".