21906744 has 32 divisors (see below), whose sum is σ = 57989520. Its totient is φ = 6872576.

The previous prime is 21906719. The next prime is 21906757. The reversal of 21906744 is 44760912.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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, 26439 + ... + 27254.

Almost surely, 2^21906744 is an apocalyptic number.

21906744 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21906744 is an abundant number, since it is smaller than the sum of its proper divisors (36082776).

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

21906744 is a wasteful number, since it uses less digits than its factorization.

21906744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53719 (or 53715 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21906744 is about 4680.4640795545. The cubic root of 21906744 is about 279.8074526555.

The spelling of 21906744 in words is "twenty-one million, nine hundred six thousand, seven hundred forty-four".