21688502 has 16 divisors (see below), whose sum is σ = 35942400. Its totient is φ = 9732840.

The previous prime is 21688483. The next prime is 21688523. The reversal of 21688502 is 20588612.

It is a super-2 number, since 2×21688502² = 940782238008008, which contains 22 as substring.

It is a congruent number.

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, 4502 + ... + 7977.

It is an arithmetic number, because the mean of its divisors is an integer number (2246400).

Almost surely, 2^21688502 is an apocalyptic number.

21688502 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21688502 is a deficient number, since it is larger than the sum of its proper divisors (14253898).

21688502 is a wasteful number, since it uses less digits than its factorization.

21688502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12571.

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 21688502 is about 4657.0915816634. The cubic root of 21688502 is about 278.8751727236.

The spelling of 21688502 in words is "twenty-one million, six hundred eighty-eight thousand, five hundred two".