21123402020 has 48 divisors (see below), whose sum is σ = 53678298240. Its totient is φ = 6816290304.

The previous prime is 21123401987. The next prime is 21123402023. The reversal of 21123402020 is 2020432112.

It is a super-2 number, since 2×21123402020² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a self number, because there is not a number n which added to its sum of digits gives 21123402020.

It is not an unprimeable number, because it can be changed into a prime (21123402023) 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, 4435310 + ... + 4440069.

It is an arithmetic number, because the mean of its divisors is an integer number (1118297880).

Almost surely, 2^21123402020 is an apocalyptic number.

21123402020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123402020 is an abundant number, since it is smaller than the sum of its proper divisors (32554896220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123402020 is a wasteful number, since it uses less digits than its factorization.

21123402020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8875412 (or 8875410 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21123402020 its reverse (2020432112), we get a palindrome (23143834132).

The spelling of 21123402020 in words is "twenty-one billion, one hundred twenty-three million, four hundred two thousand, twenty".