21961223 has 4 divisors (see below), whose sum is σ = 22270608. Its totient is φ = 21651840.

The previous prime is 21961187. The next prime is 21961243. The reversal of 21961223 is 32216912.

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

It is a cyclic number.

It is not a de Polignac number, because 21961223 - 2¹⁰ = 21960199 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21961192 and 21961201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21961243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154586 + ... + 154727.

It is an arithmetic number, because the mean of its divisors is an integer number (5567652).

Almost surely, 2^21961223 is an apocalyptic number.

21961223 is a deficient number, since it is larger than the sum of its proper divisors (309385).

21961223 is an equidigital number, since it uses as much as digits as its factorization.

21961223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309384.

The product of its digits is 1296, while the sum is 26.

The square root of 21961223 is about 4686.2802946473. The cubic root of 21961223 is about 280.0392079449.

The spelling of 21961223 in words is "twenty-one million, nine hundred sixty-one thousand, two hundred twenty-three".