19421257 has 4 divisors (see below), whose sum is σ = 19563156. Its totient is φ = 19279360.

The previous prime is 19421239. The next prime is 19421323. The reversal of 19421257 is 75212491.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75212491 = 41 ⋅1834451.

It can be written as a sum of positive squares in 2 ways, for example, as 7338681 + 12082576 = 2709^2 + 3476^2 .

It is a cyclic number.

It is not a de Polignac number, because 19421257 - 2¹¹ = 19419209 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19421557) 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, 70744 + ... + 71017.

It is an arithmetic number, because the mean of its divisors is an integer number (4890789).

Almost surely, 2^19421257 is an apocalyptic number.

It is an amenable number.

19421257 is a deficient number, since it is larger than the sum of its proper divisors (141899).

19421257 is a wasteful number, since it uses less digits than its factorization.

19421257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141898.

The product of its digits is 5040, while the sum is 31.

The square root of 19421257 is about 4406.9555250762. The cubic root of 19421257 is about 268.7978424291.

The spelling of 19421257 in words is "nineteen million, four hundred twenty-one thousand, two hundred fifty-seven".