21223961 has 4 divisors (see below), whose sum is σ = 23153424. Its totient is φ = 19294500.

The previous prime is 21223957. The next prime is 21223981. The reversal of 21223961 is 16932212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21223961 - 2² = 21223957 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21223961.

It is not an unprimeable number, because it can be changed into a prime (21223901) 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, 964715 + ... + 964736.

It is an arithmetic number, because the mean of its divisors is an integer number (5788356).

Almost surely, 2^21223961 is an apocalyptic number.

It is an amenable number.

21223961 is a deficient number, since it is larger than the sum of its proper divisors (1929463).

21223961 is a wasteful number, since it uses less digits than its factorization.

21223961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1929462.

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

The square root of 21223961 is about 4606.9470368130. The cubic root of 21223961 is about 276.8697315672.

The spelling of 21223961 in words is "twenty-one million, two hundred twenty-three thousand, nine hundred sixty-one".