21811420928 has 72 divisors (see below), whose sum is σ = 47759131056. Its totient is φ = 9859276800.

The previous prime is 21811420907. The next prime is 21811420949. The reversal of 21811420928 is 82902411812.

It is an interprime number because it is at equal distance from previous prime (21811420907) and next prime (21811420949).

It is a junction number, because it is equal to n+sod(n) for n = 21811420891 and 21811420900.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 488300 + ... + 531092.

Almost surely, 2^21811420928 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21811420928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23879565528).

21811420928 is an abundant number, since it is smaller than the sum of its proper divisors (25947710128).

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

21811420928 is a wasteful number, since it uses less digits than its factorization.

21811420928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43001 (or 42987 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 38.

The spelling of 21811420928 in words is "twenty-one billion, eight hundred eleven million, four hundred twenty thousand, nine hundred twenty-eight".