21690026 has 8 divisors (see below), whose sum is σ = 32558304. Its totient is φ = 10837260.

The previous prime is 21690013. The next prime is 21690037. The reversal of 21690026 is 62009612.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21689977 and 21690004.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 701 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (4069788).

Almost surely, 2^21690026 is an apocalyptic number.

21690026 is a deficient number, since it is larger than the sum of its proper divisors (10868278).

21690026 is a wasteful number, since it uses less digits than its factorization.

21690026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7756.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 21690026 is about 4657.2552002226. The cubic root of 21690026 is about 278.8817045380.

Adding to 21690026 its reverse (62009612), we get a palindrome (83699638).

The spelling of 21690026 in words is "twenty-one million, six hundred ninety thousand, twenty-six".