1721979648 has 126 divisors (see below), whose sum is σ = 5154050244. Its totient is φ = 573931008.

The previous prime is 1721979643. The next prime is 1721979653. The reversal of 1721979648 is 8469791271.

It is an interprime number because it is at equal distance from previous prime (1721979643) and next prime (1721979653).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 1721979594 and 1721979603.

It is not an unprimeable number, because it can be changed into a prime (1721979643) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 182011 + ... + 191237.

Almost surely, 2^1721979648 is an apocalyptic number.

1721979648 is a gapful number since it is divisible by the number (18) 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 1721979648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2577025122).

1721979648 is an abundant number, since it is smaller than the sum of its proper divisors (3432070596).

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

1721979648 is an frugal number, since it uses more digits than its factorization.

1721979648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9261 (or 9232 counting only the distinct ones).

The product of its digits is 1524096, while the sum is 54.

The square root of 1721979648 is about 41496.7426191502. The cubic root of 1721979648 is about 1198.6047784260.

The spelling of 1721979648 in words is "one billion, seven hundred twenty-one million, nine hundred seventy-nine thousand, six hundred forty-eight".