658993981 has 4 divisors (see below), whose sum is σ = 659645532. Its totient is φ = 658342432.

The previous prime is 658993957. The next prime is 658994009. The reversal of 658993981 is 189399856.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45441081 + 613552900 = 6741^2 + 24770^2 .

It is a cyclic number.

It is not a de Polignac number, because 658993981 - 2⁵ = 658993949 is a prime.

It is a super-2 number, since 2×658993981² = 868546133988456722, 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 (658993901) 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, 324256 + ... + 326281.

It is an arithmetic number, because the mean of its divisors is an integer number (164911383).

Almost surely, 2^658993981 is an apocalyptic number.

It is an amenable number.

658993981 is a deficient number, since it is larger than the sum of its proper divisors (651551).

658993981 is a wasteful number, since it uses less digits than its factorization.

658993981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 651550.

The product of its digits is 4199040, while the sum is 58.

The square root of 658993981 is about 25670.8780722437. The cubic root of 658993981 is about 870.2161707954.

The spelling of 658993981 in words is "six hundred fifty-eight million, nine hundred ninety-three thousand, nine hundred eighty-one".