1647749640 has 128 divisors (see below), whose sum is σ = 5055436800. Its totient is φ = 429515520.

The previous prime is 1647749639. The next prime is 1647749681. The reversal of 1647749640 is 469477461.

It is a super-2 number, since 2×1647749640² = 5430157752240259200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1647749640.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1493329 + ... + 1494431.

It is an arithmetic number, because the mean of its divisors is an integer number (39495600).

Almost surely, 2^1647749640 is an apocalyptic number.

1647749640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1647749640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2527718400).

1647749640 is an abundant number, since it is smaller than the sum of its proper divisors (3407687160).

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

1647749640 is a wasteful number, since it uses less digits than its factorization.

1647749640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1387 (or 1383 counting only the distinct ones).

The product of its (nonzero) digits is 1016064, while the sum is 48.

The square root of 1647749640 is about 40592.4825552712. The cubic root of 1647749640 is about 1181.1282993233.

The spelling of 1647749640 in words is "one billion, six hundred forty-seven million, seven hundred forty-nine thousand, six hundred forty".