21711690 has 192 divisors, whose sum is σ = 76108032. Its totient is φ = 4147200.

The previous prime is 21711619. The next prime is 21711709. The reversal of 21711690 is 9611712.

It is a super-2 number, since 2×21711690² = 942794965312200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 89970 + ... + 90210.

It is an arithmetic number, because the mean of its divisors is an integer number (396396).

Almost surely, 2^21711690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21711690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38054016).

21711690 is an abundant number, since it is smaller than the sum of its proper divisors (54396342).

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

21711690 is a wasteful number, since it uses less digits than its factorization.

21711690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285 (or 282 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 27.

The square root of 21711690 is about 4659.5804532168. The cubic root of 21711690 is about 278.9745226668.

The spelling of 21711690 in words is "twenty-one million, seven hundred eleven thousand, six hundred ninety".