19978673 has 18 divisors (see below), whose sum is σ = 23803542. Its totient is φ = 16748160.

The previous prime is 19978667. The next prime is 19978733. The reversal of 19978673 is 37687991.

It can be written as a sum of positive squares in 3 ways, for example, as 1385329 + 18593344 = 1177^2 + 4312^2 .

It is not a de Polignac number, because 19978673 - 2²² = 15784369 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19978613) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 19961 + ... + 20937.

It is an arithmetic number, because the mean of its divisors is an integer number (1322419).

Almost surely, 2^19978673 is an apocalyptic number.

19978673 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

19978673 is a deficient number, since it is larger than the sum of its proper divisors (3824869).

19978673 is a wasteful number, since it uses less digits than its factorization.

19978673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1025 (or 1001 counting only the distinct ones).

The product of its digits is 571536, while the sum is 50.

The square root of 19978673 is about 4469.7508879131. The cubic root of 19978673 is about 271.3452433697.

The spelling of 19978673 in words is "nineteen million, nine hundred seventy-eight thousand, six hundred seventy-three".