1621563851 has 2 divisors, whose sum is σ = 1621563852. Its totient is φ = 1621563850.

The previous prime is 1621563829. The next prime is 1621563863. The reversal of 1621563851 is 1583651261.

It is a strong prime.

It is an emirp because it is prime and its reverse (1583651261) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1621563851 - 2¹⁰ = 1621562827 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1621563551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810781925 + 810781926.

It is an arithmetic number, because the mean of its divisors is an integer number (810781926).

Almost surely, 2^1621563851 is an apocalyptic number.

1621563851 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621563851 is an equidigital number, since it uses as much as digits as its factorization.

1621563851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43200, while the sum is 38.

The square root of 1621563851 is about 40268.6460040563. The cubic root of 1621563851 is about 1174.8380886906.

The spelling of 1621563851 in words is "one billion, six hundred twenty-one million, five hundred sixty-three thousand, eight hundred fifty-one".