21701790 has 64 divisors (see below), whose sum is σ = 63141120. Its totient is φ = 5260320.

The previous prime is 21701749. The next prime is 21701803. The reversal of 21701790 is 9710712.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 684 + ... + 6623.

It is an arithmetic number, because the mean of its divisors is an integer number (986580).

Almost surely, 2^21701790 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21701790, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31570560).

21701790 is an abundant number, since it is smaller than the sum of its proper divisors (41439330).

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

21701790 is a wasteful number, since it uses less digits than its factorization.

21701790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7334 (or 7328 counting only the distinct ones).

The product of its (nonzero) digits is 882, while the sum is 27.

The square root of 21701790 is about 4658.5180046878. The cubic root of 21701790 is about 278.9321143657.

The spelling of 21701790 in words is "twenty-one million, seven hundred one thousand, seven hundred ninety".