21862638 has 48 divisors (see below), whose sum is σ = 54512640. Its totient is φ = 6203088.

The previous prime is 21862637. The next prime is 21862651. The reversal of 21862638 is 83626812.

21862638 is a `hidden beast` number, since 2 + 18 + 6 + 2 + 638 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21862637) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20523 + ... + 21561.

It is an arithmetic number, because the mean of its divisors is an integer number (1135680).

Almost surely, 2^21862638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21862638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27256320).

21862638 is an abundant number, since it is smaller than the sum of its proper divisors (32650002).

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

21862638 is a wasteful number, since it uses less digits than its factorization.

21862638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1221 (or 1218 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21862638 is about 4675.7499933166. The cubic root of 21862638 is about 279.6195428020.

It can be divided in two parts, 21862 and 638, that added together give a square (22500 = 150²).

The spelling of 21862638 in words is "twenty-one million, eight hundred sixty-two thousand, six hundred thirty-eight".