21071500 has 96 divisors (see below), whose sum is σ = 50791104. Its totient is φ = 7603200.

The previous prime is 21071497. The next prime is 21071503. The reversal of 21071500 is 517012.

It is an interprime number because it is at equal distance from previous prime (21071497) and next prime (21071503).

It is a super-2 number, since 2×21071500² = 888016224500000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21071503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 314467 + ... + 314533.

It is an arithmetic number, because the mean of its divisors is an integer number (529074).

Almost surely, 2^21071500 is an apocalyptic number.

21071500 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 21071500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25395552).

21071500 is an abundant number, since it is smaller than the sum of its proper divisors (29719604).

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

21071500 is a wasteful number, since it uses less digits than its factorization.

21071500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 16.

The square root of 21071500 is about 4590.3703554289. The cubic root of 21071500 is about 276.2051789448.

Adding to 21071500 its reverse (517012), we get a palindrome (21588512).

The spelling of 21071500 in words is "twenty-one million, seventy-one thousand, five hundred".