21701861 has 4 divisors (see below), whose sum is σ = 21727872. Its totient is φ = 21675852.

The previous prime is 21701839. The next prime is 21701873. The reversal of 21701861 is 16810712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21701861 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21701861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701821) 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, 11711 + ... + 13436.

It is an arithmetic number, because the mean of its divisors is an integer number (5431968).

Almost surely, 2^21701861 is an apocalyptic number.

It is an amenable number.

21701861 is a deficient number, since it is larger than the sum of its proper divisors (26011).

21701861 is an equidigital number, since it uses as much as digits as its factorization.

21701861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26010.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 21701861 is about 4658.5256251308. The cubic root of 21701861 is about 278.9324185520.

The spelling of 21701861 in words is "twenty-one million, seven hundred one thousand, eight hundred sixty-one".