649855981 has 8 divisors (see below), whose sum is σ = 673591680. Its totient is φ = 626533248.

The previous prime is 649855967. The next prime is 649856029. The reversal of 649855981 is 189558946.

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 649855981 - 2⁷ = 649855853 is a prime.

It is a super-2 number, since 2×649855981² = 844625592082944722, 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 (649855181) 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, 100036 + ... + 106333.

It is an arithmetic number, because the mean of its divisors is an integer number (84198960).

Almost surely, 2^649855981 is an apocalyptic number.

It is an amenable number.

649855981 is a deficient number, since it is larger than the sum of its proper divisors (23735699).

649855981 is a wasteful number, since it uses less digits than its factorization.

649855981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206483.

The product of its digits is 3110400, while the sum is 55.

The square root of 649855981 is about 25492.2729665285. The cubic root of 649855981 is about 866.1751237487.

The spelling of 649855981 in words is "six hundred forty-nine million, eight hundred fifty-five thousand, nine hundred eighty-one".