21406936 has 8 divisors (see below), whose sum is σ = 40138020. Its totient is φ = 10703464.

The previous prime is 21406933. The next prime is 21406963. The reversal of 21406936 is 63960412.

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21406898 and 21406907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406933) 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 as a sum of consecutive naturals, namely, 1337926 + ... + 1337941.

Almost surely, 2^21406936 is an apocalyptic number.

It is an amenable number.

21406936 is a deficient number, since it is larger than the sum of its proper divisors (18731084).

21406936 is a wasteful number, since it uses less digits than its factorization.

21406936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2675873 (or 2675869 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21406936 is about 4626.7630153272. The cubic root of 21406936 is about 277.6631013693.

The spelling of 21406936 in words is "twenty-one million, four hundred six thousand, nine hundred thirty-six".