1620421819 has 2 divisors, whose sum is σ = 1620421820. Its totient is φ = 1620421818.

The previous prime is 1620421769. The next prime is 1620421849. The reversal of 1620421819 is 9181240261.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1620421819 - 2¹¹ = 1620419771 is a prime.

It is a super-2 number, since 2×1620421819² = 5251533742982537522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1620421849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810210909 + 810210910.

It is an arithmetic number, because the mean of its divisors is an integer number (810210910).

Almost surely, 2^1620421819 is an apocalyptic number.

1620421819 is a deficient number, since it is larger than the sum of its proper divisors (1).

1620421819 is an equidigital number, since it uses as much as digits as its factorization.

1620421819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 1620421819 is about 40254.4633425910. The cubic root of 1620421819 is about 1174.5622196498.

The spelling of 1620421819 in words is "one billion, six hundred twenty million, four hundred twenty-one thousand, eight hundred nineteen".