21971606 has 4 divisors (see below), whose sum is σ = 32957412. Its totient is φ = 10985802.

The previous prime is 21971603. The next prime is 21971617. The reversal of 21971606 is 60617912.

It is a happy number.

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

It is a super-3 number, since 3×21971606³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21971603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5492900 + ... + 5492903.

It is an arithmetic number, because the mean of its divisors is an integer number (8239353).

Almost surely, 2^21971606 is an apocalyptic number.

21971606 is a deficient number, since it is larger than the sum of its proper divisors (10985806).

21971606 is a wasteful number, since it uses less digits than its factorization.

21971606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10985805.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 21971606 is about 4687.3879719946. The cubic root of 21971606 is about 280.0833340391.

The spelling of 21971606 in words is "twenty-one million, nine hundred seventy-one thousand, six hundred six".