21689930 has 16 divisors (see below), whose sum is σ = 39306600. Its totient is φ = 8617152.

The previous prime is 21689917. The next prime is 21689947. The reversal of 21689930 is 3998612.

21689930 = T₂₉₄₃ + T₂₉₄₄ + ... + T₂₉₄₇.

It can be written as a sum of positive squares in 4 ways, for example, as 9066121 + 12623809 = 3011^2 + 3553^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5789 + ... + 8768.

Almost surely, 2^21689930 is an apocalyptic number.

21689930 is a deficient number, since it is larger than the sum of its proper divisors (17616670).

21689930 is a wasteful number, since it uses less digits than its factorization.

21689930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14713.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21689930 is about 4657.2448937113. The cubic root of 21689930 is about 278.8812930942.

The spelling of 21689930 in words is "twenty-one million, six hundred eighty-nine thousand, nine hundred thirty".