20457842 has 4 divisors (see below), whose sum is σ = 30686766. Its totient is φ = 10228920.

The previous prime is 20457823. The next prime is 20457863. The reversal of 20457842 is 24875402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24875402 = 2 ⋅12437701.

It can be written as a sum of positive squares in only one way, i.e., 20421361 + 36481 = 4519^2 + 191^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20457799 and 20457808.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5114459 + ... + 5114462.

Almost surely, 2^20457842 is an apocalyptic number.

20457842 is a deficient number, since it is larger than the sum of its proper divisors (10228924).

20457842 is a wasteful number, since it uses less digits than its factorization.

20457842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10228923.

The product of its (nonzero) digits is 17920, while the sum is 32.

The square root of 20457842 is about 4523.0346007962. The cubic root of 20457842 is about 273.4974449059.

The spelling of 20457842 in words is "twenty million, four hundred fifty-seven thousand, eight hundred forty-two".