19971648 has 42 divisors (see below), whose sum is σ = 57246774. Its totient is φ = 6657024.

The previous prime is 19971643. The next prime is 19971667. The reversal of 19971648 is 84617991.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12616704 + 7354944 = 3552^2 + 2712^2 .

It is not an unprimeable number, because it can be changed into a prime (19971643) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 16761 + ... + 17912.

Almost surely, 2^19971648 is an apocalyptic number.

19971648 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

19971648 is an abundant number, since it is smaller than the sum of its proper divisors (37275126).

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

19971648 is a wasteful number, since it uses less digits than its factorization.

19971648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34691 (or 34678 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 19971648 is about 4468.9649808429. The cubic root of 19971648 is about 271.3134357216.

The spelling of 19971648 in words is "nineteen million, nine hundred seventy-one thousand, six hundred forty-eight".