21687358 has 16 divisors (see below), whose sum is σ = 40558464. Its totient is φ = 8449560.

The previous prime is 21687343. The next prime is 21687361. The reversal of 21687358 is 85378612.

It is a self number, because there is not a number n which added to its sum of digits gives 21687358.

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, 70260 + ... + 70567.

It is an arithmetic number, because the mean of its divisors is an integer number (2534904).

Almost surely, 2^21687358 is an apocalyptic number.

21687358 is a deficient number, since it is larger than the sum of its proper divisors (18871106).

21687358 is a wasteful number, since it uses less digits than its factorization.

21687358 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140847.

The product of its digits is 80640, while the sum is 40.

The square root of 21687358 is about 4656.9687566055. The cubic root of 21687358 is about 278.8702693758.

The spelling of 21687358 in words is "twenty-one million, six hundred eighty-seven thousand, three hundred fifty-eight".