21894729 has 8 divisors (see below), whose sum is σ = 29628960. Its totient is φ = 14378496.

The previous prime is 21894703. The next prime is 21894737. The reversal of 21894729 is 92749812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21894729 - 2¹⁶ = 21829193 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21894329) 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, 54264 + ... + 54665.

It is an arithmetic number, because the mean of its divisors is an integer number (3703620).

Almost surely, 2^21894729 is an apocalyptic number.

It is an amenable number.

21894729 is a deficient number, since it is larger than the sum of its proper divisors (7734231).

21894729 is a wasteful number, since it uses less digits than its factorization.

21894729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108999.

The product of its digits is 72576, while the sum is 42.

The square root of 21894729 is about 4679.1803769464. The cubic root of 21894729 is about 279.7562887863.

The spelling of 21894729 in words is "twenty-one million, eight hundred ninety-four thousand, seven hundred twenty-nine".