21355966 has 4 divisors (see below), whose sum is σ = 32033952. Its totient is φ = 10677982.

The previous prime is 21355963. The next prime is 21355967. The reversal of 21355966 is 66955312.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5338990 + ... + 5338993.

It is an arithmetic number, because the mean of its divisors is an integer number (8008488).

Almost surely, 2^21355966 is an apocalyptic number.

21355966 is a deficient number, since it is larger than the sum of its proper divisors (10677986).

21355966 is a wasteful number, since it uses less digits than its factorization.

21355966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10677985.

The product of its digits is 48600, while the sum is 37.

The square root of 21355966 is about 4621.2515620771. The cubic root of 21355966 is about 277.4425539178.

The spelling of 21355966 in words is "twenty-one million, three hundred fifty-five thousand, nine hundred sixty-six".