20991026 has 8 divisors (see below), whose sum is σ = 35984640. Its totient is φ = 8996148.

The previous prime is 20991023. The next prime is 20991043. The reversal of 20991026 is 62019902.

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

It is a self number, because there is not a number n which added to its sum of digits gives 20991026.

It is not an unprimeable number, because it can be changed into a prime (20991023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 749666 + ... + 749693.

It is an arithmetic number, because the mean of its divisors is an integer number (4498080).

Almost surely, 2^20991026 is an apocalyptic number.

20991026 is a deficient number, since it is larger than the sum of its proper divisors (14993614).

20991026 is a wasteful number, since it uses less digits than its factorization.

20991026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1499368.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 20991026 is about 4581.5964466548. The cubic root of 20991026 is about 275.8531126967.

It can be divided in two parts, 2099 and 1026, that added together give a 5-th power (3125 = 5⁵).

The spelling of 20991026 in words is "twenty million, nine hundred ninety-one thousand, twenty-six".