21861455 has 16 divisors (see below), whose sum is σ = 32707584. Its totient is φ = 13627680.

The previous prime is 21861451. The next prime is 21861461. The reversal of 21861455 is 55416812.

It is not a de Polignac number, because 21861455 - 2² = 21861451 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28007 + ... + 28776.

It is an arithmetic number, because the mean of its divisors is an integer number (2044224).

Almost surely, 2^21861455 is an apocalyptic number.

21861455 is a deficient number, since it is larger than the sum of its proper divisors (10846129).

21861455 is a wasteful number, since it uses less digits than its factorization.

21861455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56806.

The product of its digits is 9600, while the sum is 32.

The square root of 21861455 is about 4675.6234878356. The cubic root of 21861455 is about 279.6144992525.

The spelling of 21861455 in words is "twenty-one million, eight hundred sixty-one thousand, four hundred fifty-five".