21101706 has 12 divisors (see below), whose sum is σ = 45720402. Its totient is φ = 7033896.

The previous prime is 21101701. The next prime is 21101737. The reversal of 21101706 is 60710112.

It can be written as a sum of positive squares in only one way, i.e., 17264025 + 3837681 = 4155^2 + 1959^2 .

It is a super-2 number, since 2×21101706² = 890563992220872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1172317 = 21101706 / (2 + 1 + 1 + 0 + 1 + 7 + 0 + 6).

It is a zygodrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21101701) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 586141 + ... + 586176.

Almost surely, 2^21101706 is an apocalyptic number.

21101706 is an abundant number, since it is smaller than the sum of its proper divisors (24618696).

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

21101706 is a wasteful number, since it uses less digits than its factorization.

21101706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1172325 (or 1172322 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 18.

The square root of 21101706 is about 4593.6593256357. The cubic root of 21101706 is about 276.3370959925.

Adding to 21101706 its reverse (60710112), we get a palindrome (81811818).

The spelling of 21101706 in words is "twenty-one million, one hundred one thousand, seven hundred six".