21700061 has 4 divisors (see below), whose sum is σ = 21718332. Its totient is φ = 21681792.

The previous prime is 21700057. The next prime is 21700073. The reversal of 21700061 is 16000712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8231161 + 13468900 = 2869^2 + 3670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21700061 - 2² = 21700057 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21700001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7220 + ... + 9773.

It is an arithmetic number, because the mean of its divisors is an integer number (5429583).

Almost surely, 2^21700061 is an apocalyptic number.

It is an amenable number.

21700061 is a deficient number, since it is larger than the sum of its proper divisors (18271).

21700061 is a wasteful number, since it uses less digits than its factorization.

21700061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18270.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21700061 is about 4658.3324269528. The cubic root of 21700061 is about 278.9247065830.

Adding to 21700061 its reverse (16000712), we get a palindrome (37700773).

The spelling of 21700061 in words is "twenty-one million, seven hundred thousand, sixty-one".