21310819 has 2 divisors, whose sum is σ = 21310820. Its totient is φ = 21310818.

The previous prime is 21310813. The next prime is 21310841. The reversal of 21310819 is 91801312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21310819 - 2¹⁷ = 21179747 is a prime.

It is a super-2 number, since 2×21310819² = 908302012901522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21310793 and 21310802.

It is not a weakly prime, because it can be changed into another prime (21310813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655409 + 10655410.

It is an arithmetic number, because the mean of its divisors is an integer number (10655410).

Almost surely, 2^21310819 is an apocalyptic number.

21310819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310819 is an equidigital number, since it uses as much as digits as its factorization.

21310819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 21310819 is about 4616.3642620573. The cubic root of 21310819 is about 277.2469093549.

The spelling of 21310819 in words is "twenty-one million, three hundred ten thousand, eight hundred nineteen".