21550542020 has 36 divisors (see below), whose sum is σ = 52644897900. Its totient is φ = 7388756928.

The previous prime is 21550542017. The next prime is 21550542023. The reversal of 21550542020 is 2024505512.

It is an interprime number because it is at equal distance from previous prime (21550542017) and next prime (21550542023).

It can be written as a sum of positive squares in 2 ways, for example, as 3961947136 + 17588594884 = 62944^2 + 132622^2 .

It is a super-2 number, since 2×21550542020² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21550542023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10994195 + ... + 10996154.

It is an arithmetic number, because the mean of its divisors is an integer number (1462358275).

Almost surely, 2^21550542020 is an apocalyptic number.

21550542020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21550542020 is an abundant number, since it is smaller than the sum of its proper divisors (31094355880).

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

21550542020 is a wasteful number, since it uses less digits than its factorization.

21550542020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21990372 (or 21990363 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 26.

The spelling of 21550542020 in words is "twenty-one billion, five hundred fifty million, five hundred forty-two thousand, twenty".