21791020 has 12 divisors (see below), whose sum is σ = 45761184. Its totient is φ = 8716400.

The previous prime is 21791017. The next prime is 21791023. The reversal of 21791020 is 2019712.

It is an interprime number because it is at equal distance from previous prime (21791017) and next prime (21791023).

It is a junction number, because it is equal to n+sod(n) for n = 21790982 and 21791000.

It is not an unprimeable number, because it can be changed into a prime (21791023) 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, 544756 + ... + 544795.

It is an arithmetic number, because the mean of its divisors is an integer number (3813432).

Almost surely, 2^21791020 is an apocalyptic number.

21791020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21791020 is an abundant number, since it is smaller than the sum of its proper divisors (23970164).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21791020 is a wasteful number, since it uses less digits than its factorization.

21791020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1089560 (or 1089558 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21791020 is about 4668.0852605753. The cubic root of 21791020 is about 279.3138813162.

The spelling of 21791020 in words is "twenty-one million, seven hundred ninety-one thousand, twenty".