21393966 has 16 divisors (see below), whose sum is σ = 46677888. Its totient is φ = 6483000.

The previous prime is 21393961. The next prime is 21393989. The reversal of 21393966 is 66939312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21393961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162010 + ... + 162141.

It is an arithmetic number, because the mean of its divisors is an integer number (2917368).

Almost surely, 2^21393966 is an apocalyptic number.

21393966 is an abundant number, since it is smaller than the sum of its proper divisors (25283922).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21393966 is a wasteful number, since it uses less digits than its factorization.

21393966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324167.

The product of its digits is 52488, while the sum is 39.

The square root of 21393966 is about 4625.3611750868. The cubic root of 21393966 is about 277.6070133489.

It can be divided in two parts, 2139 and 3966, that added together give a triangular number (6105 = T₁₁₀).

The spelling of 21393966 in words is "twenty-one million, three hundred ninety-three thousand, nine hundred sixty-six".