21820220040 has 32 divisors (see below), whose sum is σ = 65460660480. Its totient is φ = 5818725312.

The previous prime is 21820220017. The next prime is 21820220041. The reversal of 21820220040 is 4002202812.

It is a happy number.

It is a super-2 number, since 2×21820220040² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21820219989 and 21820220016.

It is not an unprimeable number, because it can be changed into a prime (21820220041) 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, 90917464 + ... + 90917703.

It is an arithmetic number, because the mean of its divisors is an integer number (2045645640).

Almost surely, 2^21820220040 is an apocalyptic number.

21820220040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21820220040 is an abundant number, since it is smaller than the sum of its proper divisors (43640440440).

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

21820220040 is a wasteful number, since it uses less digits than its factorization.

21820220040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181835181 (or 181835177 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

Adding to 21820220040 its reverse (4002202812), we get a palindrome (25822422852).

It can be divided in two parts, 21820 and 220040, that added together give a triangular number (241860 = T₆₉₅).

The spelling of 21820220040 in words is "twenty-one billion, eight hundred twenty million, two hundred twenty thousand, forty".