19951231 has 2 divisors, whose sum is σ = 19951232. Its totient is φ = 19951230.

The previous prime is 19951229. The next prime is 19951241. The reversal of 19951231 is 13215991.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (13215991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19951231 - 2¹ = 19951229 is a prime.

It is a super-2 number, since 2×19951231² = 796103236830722, which contains 22 as substring.

Together with 19951229, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 19951193 and 19951202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19951201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9975615 + 9975616.

It is an arithmetic number, because the mean of its divisors is an integer number (9975616).

Almost surely, 2^19951231 is an apocalyptic number.

19951231 is a deficient number, since it is larger than the sum of its proper divisors (1).

19951231 is an equidigital number, since it uses as much as digits as its factorization.

19951231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2430, while the sum is 31.

The square root of 19951231 is about 4466.6800870445. The cubic root of 19951231 is about 271.2209496946.

The spelling of 19951231 in words is "nineteen million, nine hundred fifty-one thousand, two hundred thirty-one".