21807798 has 16 divisors (see below), whose sum is σ = 43676976. Its totient is φ = 7259040.

The previous prime is 21807791. The next prime is 21807803. The reversal of 21807798 is 89770812.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21807791) 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, 2988 + ... + 7248.

It is an arithmetic number, because the mean of its divisors is an integer number (2729811).

Almost surely, 2^21807798 is an apocalyptic number.

21807798 is an abundant number, since it is smaller than the sum of its proper divisors (21869178).

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

21807798 is a wasteful number, since it uses less digits than its factorization.

21807798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5119.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 21807798 is about 4669.8820113575. The cubic root of 21807798 is about 279.3855488512.

The spelling of 21807798 in words is "twenty-one million, eight hundred seven thousand, seven hundred ninety-eight".