21011020623 has 8 divisors (see below), whose sum is σ = 31127438000. Its totient is φ = 14007347064.

The previous prime is 21011020609. The next prime is 21011020627. The reversal of 21011020623 is 32602011012.

21011020623 is a `hidden beast` number, since 2 + 10 + 1 + 10 + 20 + 623 = 666.

It is not a de Polignac number, because 21011020623 - 2⁹ = 21011020111 is a prime.

It is a super-3 number, since 3×21011020623³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011020596 and 21011020605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011020627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389092948 + ... + 389093001.

It is an arithmetic number, because the mean of its divisors is an integer number (3890929750).

Almost surely, 2^21011020623 is an apocalyptic number.

21011020623 is a deficient number, since it is larger than the sum of its proper divisors (10116417377).

21011020623 is an equidigital number, since it uses as much as digits as its factorization.

21011020623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778185958 (or 778185952 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21011020623 its reverse (32602011012), we get a palindrome (53613031635).

The spelling of 21011020623 in words is "twenty-one billion, eleven million, twenty thousand, six hundred twenty-three".