21731319 has 6 divisors (see below), whose sum is σ = 31389696. Its totient is φ = 14487540.

The previous prime is 21731317. The next prime is 21731363. The reversal of 21731319 is 91313712.

It is not a de Polignac number, because 21731319 - 2¹ = 21731317 is a prime.

It is a super-2 number, since 2×21731319² = 944500450959522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21731292 and 21731301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21731317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207287 + ... + 1207304.

It is an arithmetic number, because the mean of its divisors is an integer number (5231616).

Almost surely, 2^21731319 is an apocalyptic number.

21731319 is a deficient number, since it is larger than the sum of its proper divisors (9658377).

21731319 is a wasteful number, since it uses less digits than its factorization.

21731319 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2414597 (or 2414594 counting only the distinct ones).

The product of its digits is 1134, while the sum is 27.

The square root of 21731319 is about 4661.6862828809. The cubic root of 21731319 is about 279.0585686577.

The spelling of 21731319 in words is "twenty-one million, seven hundred thirty-one thousand, three hundred nineteen".