21693646 has 16 divisors (see below), whose sum is σ = 36568224. Its totient is φ = 9576864.

The previous prime is 21693641. The next prime is 21693667. The reversal of 21693646 is 64639612.

It is a happy number.

It is a super-2 number, since 2×21693646² = 941228553546632, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21693641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17541 + ... + 18736.

It is an arithmetic number, because the mean of its divisors is an integer number (2285514).

Almost surely, 2^21693646 is an apocalyptic number.

21693646 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21693646 is a deficient number, since it is larger than the sum of its proper divisors (14874578).

21693646 is a wasteful number, since it uses less digits than its factorization.

21693646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36315.

The product of its digits is 46656, while the sum is 37.

The square root of 21693646 is about 4657.6438249398. The cubic root of 21693646 is about 278.8972185138.

The spelling of 21693646 in words is "twenty-one million, six hundred ninety-three thousand, six hundred forty-six".