21671278 has 4 divisors (see below), whose sum is σ = 32506920. Its totient is φ = 10835638.

The previous prime is 21671261. The next prime is 21671297. The reversal of 21671278 is 87217612.

It is a happy number.

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

It is a super-3 number, since 3×21671278³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5417818 + ... + 5417821.

It is an arithmetic number, because the mean of its divisors is an integer number (8126730).

Almost surely, 2^21671278 is an apocalyptic number.

21671278 is a deficient number, since it is larger than the sum of its proper divisors (10835642).

21671278 is a wasteful number, since it uses less digits than its factorization.

21671278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10835641.

The product of its digits is 9408, while the sum is 34.

The square root of 21671278 is about 4655.2419915618. The cubic root of 21671278 is about 278.8013299402.

The spelling of 21671278 in words is "twenty-one million, six hundred seventy-one thousand, two hundred seventy-eight".