21689998 has 16 divisors (see below), whose sum is σ = 35564544. Its totient is φ = 9839160.

The previous prime is 21689981. The next prime is 21690013. The reversal of 21689998 is 89998612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19411 + ... + 20497.

It is an arithmetic number, because the mean of its divisors is an integer number (2222784).

Almost surely, 2^21689998 is an apocalyptic number.

21689998 is a deficient number, since it is larger than the sum of its proper divisors (13874546).

21689998 is a wasteful number, since it uses less digits than its factorization.

21689998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2007.

The product of its digits is 559872, while the sum is 52.

The square root of 21689998 is about 4657.2521941591. The cubic root of 21689998 is about 278.8815845337.

It can be divided in two parts, 2 and 1689998, that added together give a square (1690000 = 1300²).

The spelling of 21689998 in words is "twenty-one million, six hundred eighty-nine thousand, nine hundred ninety-eight".