21290070 has 64 divisors (see below), whose sum is σ = 55157760. Its totient is φ = 5241600.

The previous prime is 21290039. The next prime is 21290083. The reversal of 21290070 is 7009212.

It is a happy number.

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 31 ways as a sum of consecutive naturals, for example, 22915 + ... + 23825.

It is an arithmetic number, because the mean of its divisors is an integer number (861840).

Almost surely, 2^21290070 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21290070, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27578880).

21290070 is an abundant number, since it is smaller than the sum of its proper divisors (33867690).

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

21290070 is a wasteful number, since it uses less digits than its factorization.

21290070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 981.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 21290070 is about 4614.1163834476. The cubic root of 21290070 is about 277.1569008618.

Adding to 21290070 its reverse (7009212), we get a palindrome (28299282).

The spelling of 21290070 in words is "twenty-one million, two hundred ninety thousand, seventy".