21080070 has 96 divisors (see below), whose sum is σ = 60652800. Its totient is φ = 5037120.

The previous prime is 21080069. The next prime is 21080077. The reversal of 21080070 is 7008012.

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 not an unprimeable number, because it can be changed into a prime (21080077) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 105831 + ... + 106029.

It is an arithmetic number, because the mean of its divisors is an integer number (631800).

Almost surely, 2^21080070 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21080070, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30326400).

21080070 is an abundant number, since it is smaller than the sum of its proper divisors (39572730).

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

21080070 is a wasteful number, since it uses less digits than its factorization.

21080070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 21080070 is about 4591.3037364130. The cubic root of 21080070 is about 276.2426190503.

Adding to 21080070 its reverse (7008012), we get a palindrome (28088082).

The spelling of 21080070 in words is "twenty-one million, eighty thousand, seventy".