21361668 has 24 divisors (see below), whose sum is σ = 50178240. Its totient is φ = 7072800.

The previous prime is 21361619. The next prime is 21361709. The reversal of 21361668 is 86616312.

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, 4083 + ... + 7706.

It is an arithmetic number, because the mean of its divisors is an integer number (2090760).

Almost surely, 2^21361668 is an apocalyptic number.

It is an amenable number.

21361668 is an abundant number, since it is smaller than the sum of its proper divisors (28816572).

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

21361668 is a wasteful number, since it uses less digits than its factorization.

21361668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11947 (or 11945 counting only the distinct ones).

The product of its digits is 10368, while the sum is 33.

The square root of 21361668 is about 4621.8684533422. The cubic root of 21361668 is about 277.4672439220.

The spelling of 21361668 in words is "twenty-one million, three hundred sixty-one thousand, six hundred sixty-eight".