1621799851 has 16 divisors (see below), whose sum is σ = 1937447424. Its totient is φ = 1327353984.

The previous prime is 1621799849. The next prime is 1621799917. The reversal of 1621799851 is 1589971261.

It is a cyclic number.

It is not a de Polignac number, because 1621799851 - 2¹ = 1621799849 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1621799795 and 1621799804.

It is not an unprimeable number, because it can be changed into a prime (1621799801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86980 + ... + 103966.

It is an arithmetic number, because the mean of its divisors is an integer number (121090464).

Almost surely, 2^1621799851 is an apocalyptic number.

1621799851 is a deficient number, since it is larger than the sum of its proper divisors (315647573).

1621799851 is a wasteful number, since it uses less digits than its factorization.

1621799851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17610.

The product of its digits is 272160, while the sum is 49.

The square root of 1621799851 is about 40271.5762169796. The cubic root of 1621799851 is about 1174.8950806574.

The spelling of 1621799851 in words is "one billion, six hundred twenty-one million, seven hundred ninety-nine thousand, eight hundred fifty-one".