20921519 has 2 divisors, whose sum is σ = 20921520. Its totient is φ = 20921518.

The previous prime is 20921507. The next prime is 20921623. The reversal of 20921519 is 91512902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20921519 - 2¹⁶ = 20855983 is a prime.

It is a super-2 number, since 2×20921519² = 875419914534722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20921491 and 20921500.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20921119) 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 as a sum of consecutive naturals, namely, 10460759 + 10460760.

It is an arithmetic number, because the mean of its divisors is an integer number (10460760).

Almost surely, 2^20921519 is an apocalyptic number.

20921519 is a deficient number, since it is larger than the sum of its proper divisors (1).

20921519 is an equidigital number, since it uses as much as digits as its factorization.

20921519 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 20921519 is about 4574.0047004786. The cubic root of 20921519 is about 275.5483010999.

The spelling of 20921519 in words is "twenty million, nine hundred twenty-one thousand, five hundred nineteen".