642437981 has 8 divisors (see below), whose sum is σ = 647002080. Its totient is φ = 637885072.

The previous prime is 642437969. The next prime is 642437989. The reversal of 642437981 is 189734246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642437981 - 2¹⁸ = 642175837 is a prime.

It is a super-2 number, since 2×642437981² = 825453118862712722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642437989) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136046 + ... + 140688.

It is an arithmetic number, because the mean of its divisors is an integer number (80875260).

Almost surely, 2^642437981 is an apocalyptic number.

It is an amenable number.

642437981 is a deficient number, since it is larger than the sum of its proper divisors (4564099).

642437981 is a wasteful number, since it uses less digits than its factorization.

642437981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5595.

The product of its digits is 290304, while the sum is 44.

The square root of 642437981 is about 25346.3603107034. The cubic root of 642437981 is about 862.8667542268.

The spelling of 642437981 in words is "six hundred forty-two million, four hundred thirty-seven thousand, nine hundred eighty-one".