19782121 has 2 divisors, whose sum is σ = 19782122. Its totient is φ = 19782120.

The previous prime is 19782109. The next prime is 19782127. The reversal of 19782121 is 12128791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19669225 + 112896 = 4435^2 + 336^2 .

It is a cyclic number.

It is not a de Polignac number, because 19782121 - 2¹¹ = 19780073 is a prime.

It is a super-2 number, since 2×19782121² = 782664622517282, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19782127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9891060 + 9891061.

It is an arithmetic number, because the mean of its divisors is an integer number (9891061).

Almost surely, 2^19782121 is an apocalyptic number.

It is an amenable number.

19782121 is a deficient number, since it is larger than the sum of its proper divisors (1).

19782121 is an equidigital number, since it uses as much as digits as its factorization.

19782121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 31.

The square root of 19782121 is about 4447.7096353067. The cubic root of 19782121 is about 270.4524694887.

The spelling of 19782121 in words is "nineteen million, seven hundred eighty-two thousand, one hundred twenty-one".