21782419 has 2 divisors, whose sum is σ = 21782420. Its totient is φ = 21782418.

The previous prime is 21782407. The next prime is 21782447. The reversal of 21782419 is 91428712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21782419 - 2¹⁷ = 21651347 is a prime.

It is a super-2 number, since 2×21782419² = 948947554983122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21782819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10891209 + 10891210.

It is an arithmetic number, because the mean of its divisors is an integer number (10891210).

Almost surely, 2^21782419 is an apocalyptic number.

21782419 is a deficient number, since it is larger than the sum of its proper divisors (1).

21782419 is an equidigital number, since it uses as much as digits as its factorization.

21782419 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 34.

The square root of 21782419 is about 4667.1639139846. The cubic root of 21782419 is about 279.2771277232.

It can be divided in two parts, 21782 and 419, that added together give a square (22201 = 149²).

The spelling of 21782419 in words is "twenty-one million, seven hundred eighty-two thousand, four hundred nineteen".