21820519801 has 4 divisors (see below), whose sum is σ = 21823635600. Its totient is φ = 21817404004.

The previous prime is 21820519789. The next prime is 21820519811. The reversal of 21820519801 is 10891502812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21820519801 - 2¹⁷ = 21820388729 is a prime.

It is a super-2 number, since 2×21820519801² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21820519811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1547371 + ... + 1561408.

It is an arithmetic number, because the mean of its divisors is an integer number (5455908900).

Almost surely, 2^21820519801 is an apocalyptic number.

It is an amenable number.

21820519801 is a deficient number, since it is larger than the sum of its proper divisors (3115799).

21820519801 is an equidigital number, since it uses as much as digits as its factorization.

21820519801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3115798.

The product of its (nonzero) digits is 11520, while the sum is 37.

The spelling of 21820519801 in words is "twenty-one billion, eight hundred twenty million, five hundred nineteen thousand, eight hundred one".