21355716 has 48 divisors (see below), whose sum is σ = 52113600. Its totient is φ = 6797952.

The previous prime is 21355693. The next prime is 21355717. The reversal of 21355716 is 61755312.

It is not an unprimeable number, because it can be changed into a prime (21355717) 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, 37651 + ... + 38213.

It is an arithmetic number, because the mean of its divisors is an integer number (1085700).

Almost surely, 2^21355716 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 21355716, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26056800).

21355716 is an abundant number, since it is smaller than the sum of its proper divisors (30757884).

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

21355716 is a wasteful number, since it uses less digits than its factorization.

21355716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708 (or 706 counting only the distinct ones).

The product of its digits is 6300, while the sum is 30.

The square root of 21355716 is about 4621.2245130485. The cubic root of 21355716 is about 277.4414713021.

The spelling of 21355716 in words is "twenty-one million, three hundred fifty-five thousand, seven hundred sixteen".