21858955 has 4 divisors (see below), whose sum is σ = 26230752. Its totient is φ = 17487160.

The previous prime is 21858931. The next prime is 21858979. The reversal of 21858955 is 55985812.

21858955 is nontrivially palindromic in base 12.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21858931) and next prime (21858979).

It is not a de Polignac number, because 21858955 - 2¹⁵ = 21826187 is a prime.

It is a super-3 number, since 3×21858955³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2185891 + ... + 2185900.

It is an arithmetic number, because the mean of its divisors is an integer number (6557688).

Almost surely, 2^21858955 is an apocalyptic number.

21858955 is a deficient number, since it is larger than the sum of its proper divisors (4371797).

21858955 is an equidigital number, since it uses as much as digits as its factorization.

21858955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4371796.

The product of its digits is 144000, while the sum is 43.

The square root of 21858955 is about 4675.3561361676. The cubic root of 21858955 is about 279.6038402655.

The spelling of 21858955 in words is "twenty-one million, eight hundred fifty-eight thousand, nine hundred fifty-five".