21611070 has 128 divisors (see below), whose sum is σ = 63866880. Its totient is φ = 5166720.

The previous prime is 21611041. The next prime is 21611087. The reversal of 21611070 is 7011612.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 164905 + ... + 165035.

It is an arithmetic number, because the mean of its divisors is an integer number (498960).

Almost surely, 2^21611070 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21611070, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31933440).

21611070 is an abundant number, since it is smaller than the sum of its proper divisors (42255810).

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

21611070 is a wasteful number, since it uses less digits than its factorization.

21611070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207 (or 201 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 18.

The square root of 21611070 is about 4648.7708052775. The cubic root of 21611070 is about 278.5428981770.

Adding to 21611070 its reverse (7011612), we get a palindrome (28622682).

The spelling of 21611070 in words is "twenty-one million, six hundred eleven thousand, seventy".