21691120 has 60 divisors (see below), whose sum is σ = 55369224. Its totient is φ = 7837440.

The previous prime is 21691097. The next prime is 21691121. The reversal of 21691120 is 2119612.

It is a hoax number, since the sum of its digits (22) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21691091 and 21691100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 138082 + ... + 138238.

Almost surely, 2^21691120 is an apocalyptic number.

21691120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21691120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27684612).

21691120 is an abundant number, since it is smaller than the sum of its proper divisors (33678104).

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

21691120 is a wasteful number, since it uses less digits than its factorization.

21691120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 21691120 is about 4657.3726498961. The cubic root of 21691120 is about 278.8863931978.

The spelling of 21691120 in words is "twenty-one million, six hundred ninety-one thousand, one hundred twenty".