649691988 has 96 divisors (see below), whose sum is σ = 1751016960. Its totient is φ = 185619840.

The previous prime is 649691983. The next prime is 649691989. The reversal of 649691988 is 889196946.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (649691981) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 162631 + ... + 166577.

It is an arithmetic number, because the mean of its divisors is an integer number (18239760).

Almost surely, 2^649691988 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 649691988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (875508480).

649691988 is an abundant number, since it is smaller than the sum of its proper divisors (1101324972).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

649691988 is a wasteful number, since it uses less digits than its factorization.

649691988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4037 (or 4035 counting only the distinct ones).

The product of its digits is 6718464, while the sum is 60.

The square root of 649691988 is about 25489.0562398846. The cubic root of 649691988 is about 866.1022570359.

The spelling of 649691988 in words is "six hundred forty-nine million, six hundred ninety-one thousand, nine hundred eighty-eight".