21860001 has 6 divisors (see below), whose sum is σ = 31575570. Its totient is φ = 14573328.

The previous prime is 21859987. The next prime is 21860057. The reversal of 21860001 is 10006812.

It can be written as a sum of positive squares in only one way, i.e., 18533025 + 3326976 = 4305^2 + 1824^2 .

It is not a de Polignac number, because 21860001 - 2¹⁴ = 21843617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21860401) 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, 1214436 + ... + 1214453.

It is an arithmetic number, because the mean of its divisors is an integer number (5262595).

Almost surely, 2^21860001 is an apocalyptic number.

It is an amenable number.

21860001 is a deficient number, since it is larger than the sum of its proper divisors (9715569).

21860001 is a wasteful number, since it uses less digits than its factorization.

21860001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2428895 (or 2428892 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21860001 is about 4675.4679979656. The cubic root of 21860001 is about 279.6083000845.

Adding to 21860001 its reverse (10006812), we get a palindrome (31866813).

The spelling of 21860001 in words is "twenty-one million, eight hundred sixty thousand, one".