21861396 has 18 divisors (see below), whose sum is σ = 55260842. Its totient is φ = 7287120.

The previous prime is 21861391. The next prime is 21861401. The reversal of 21861396 is 69316812.

It is an interprime number because it is at equal distance from previous prime (21861391) and next prime (21861401).

It can be written as a sum of positive squares in only one way, i.e., 19236996 + 2624400 = 4386^2 + 1620^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 607261 = 21861396 / (2 + 1 + 8 + 6 + 1 + 3 + 9 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 21861396.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861391) 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, 303595 + ... + 303666.

Almost surely, 2^21861396 is an apocalyptic number.

It is an amenable number.

21861396 is an abundant number, since it is smaller than the sum of its proper divisors (33399446).

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

21861396 is a wasteful number, since it uses less digits than its factorization.

21861396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607271 (or 607266 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21861396 is about 4675.6171785124. The cubic root of 21861396 is about 279.6142477098.

The spelling of 21861396 in words is "twenty-one million, eight hundred sixty-one thousand, three hundred ninety-six".