21686967 has 16 divisors (see below), whose sum is σ = 32428000. Its totient is φ = 14323392.

The previous prime is 21686957. The next prime is 21686971. The reversal of 21686967 is 76968612.

It is not a de Polignac number, because 21686967 - 2¹⁹ = 21162679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21686927) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 742 + ... + 6627.

It is an arithmetic number, because the mean of its divisors is an integer number (2026750).

Almost surely, 2^21686967 is an apocalyptic number.

21686967 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21686967 is a deficient number, since it is larger than the sum of its proper divisors (10741033).

21686967 is a wasteful number, since it uses less digits than its factorization.

21686967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7487 (or 7481 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 21686967 is about 4656.9267763193. The cubic root of 21686967 is about 278.8685934543.

The spelling of 21686967 in words is "twenty-one million, six hundred eighty-six thousand, nine hundred sixty-seven".