19978057 has 4 divisors (see below), whose sum is σ = 21794256. Its totient is φ = 18161860.

The previous prime is 19978037. The next prime is 19978067. The reversal of 19978057 is 75087991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19978057 is a prime.

It is a super-2 number, since 2×19978057² = 798245522990498, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19977998 and 19978016.

It is not an unprimeable number, because it can be changed into a prime (19978037) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 908083 + ... + 908104.

It is an arithmetic number, because the mean of its divisors is an integer number (5448564).

Almost surely, 2^19978057 is an apocalyptic number.

It is an amenable number.

19978057 is a deficient number, since it is larger than the sum of its proper divisors (1816199).

19978057 is a wasteful number, since it uses less digits than its factorization.

19978057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1816198.

The product of its (nonzero) digits is 158760, while the sum is 46.

The square root of 19978057 is about 4469.6819797386. The cubic root of 19978057 is about 271.3424545561.

The spelling of 19978057 in words is "nineteen million, nine hundred seventy-eight thousand, fifty-seven".