21665674 has 4 divisors (see below), whose sum is σ = 32498514. Its totient is φ = 10832836.

The previous prime is 21665653. The next prime is 21665689. The reversal of 21665674 is 47656612.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 21095649 + 570025 = 4593^2 + 755^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5416417 + ... + 5416420.

Almost surely, 2^21665674 is an apocalyptic number.

21665674 is a deficient number, since it is larger than the sum of its proper divisors (10832840).

21665674 is a wasteful number, since it uses less digits than its factorization.

21665674 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10832839.

The product of its digits is 60480, while the sum is 37.

The square root of 21665674 is about 4654.6400505302. The cubic root of 21665674 is about 278.7772960193. Note that the first 3 decimals are identical.

The spelling of 21665674 in words is "twenty-one million, six hundred sixty-five thousand, six hundred seventy-four".