642220687 has 4 divisors (see below), whose sum is σ = 643561920. Its totient is φ = 640879456.

The previous prime is 642220637. The next prime is 642220703. The reversal of 642220687 is 786022246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 786022246 = 2 ⋅393011123.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642220687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642220637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 669898 + ... + 670855.

It is an arithmetic number, because the mean of its divisors is an integer number (160890480).

Almost surely, 2^642220687 is an apocalyptic number.

642220687 is a deficient number, since it is larger than the sum of its proper divisors (1341233).

642220687 is a wasteful number, since it uses less digits than its factorization.

642220687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341232.

The product of its (nonzero) digits is 64512, while the sum is 37.

The square root of 642220687 is about 25342.0734550273. The cubic root of 642220687 is about 862.7694597967.

The spelling of 642220687 in words is "six hundred forty-two million, two hundred twenty thousand, six hundred eighty-seven".