21949123 has 16 divisors (see below), whose sum is σ = 26752000. Its totient is φ = 17589312.

The previous prime is 21949111. The next prime is 21949139. The reversal of 21949123 is 32194912.

It is a cyclic number.

It is not a de Polignac number, because 21949123 - 2⁹ = 21948611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21949163) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9463 + ... + 11551.

It is an arithmetic number, because the mean of its divisors is an integer number (1672000).

Almost surely, 2^21949123 is an apocalyptic number.

21949123 is a deficient number, since it is larger than the sum of its proper divisors (4802877).

21949123 is a wasteful number, since it uses less digits than its factorization.

21949123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2194.

The product of its digits is 3888, while the sum is 31.

The square root of 21949123 is about 4684.9891141816. The cubic root of 21949123 is about 279.9877673227.

The spelling of 21949123 in words is "twenty-one million, nine hundred forty-nine thousand, one hundred twenty-three".