19902431 has 4 divisors (see below), whose sum is σ = 19928952. Its totient is φ = 19875912.

The previous prime is 19902413. The next prime is 19902451. The reversal of 19902431 is 13420991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13420991 = 47 ⋅285553.

It is a cyclic number.

It is not a de Polignac number, because 19902431 - 2¹⁴ = 19886047 is a prime.

It is a super-2 number, since 2×19902431² = 792213519419522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19902394 and 19902403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19902451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12101 + ... + 13646.

It is an arithmetic number, because the mean of its divisors is an integer number (4982238).

Almost surely, 2^19902431 is an apocalyptic number.

19902431 is a deficient number, since it is larger than the sum of its proper divisors (26521).

19902431 is an equidigital number, since it uses as much as digits as its factorization.

19902431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26520.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 19902431 is about 4461.2140724247. The cubic root of 19902431 is about 270.9996368963. Note that the first 3 decimals are identical.

The spelling of 19902431 in words is "nineteen million, nine hundred two thousand, four hundred thirty-one".