21123458 has 4 divisors (see below), whose sum is σ = 31685190. Its totient is φ = 10561728.

The previous prime is 21123457. The next prime is 21123461. The reversal of 21123458 is 85432112.

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

It can be written as a sum of positive squares in only one way, i.e., 20097289 + 1026169 = 4483^2 + 1013^2 .

It is not an unprimeable number, because it can be changed into a prime (21123457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5280863 + ... + 5280866.

Almost surely, 2^21123458 is an apocalyptic number.

21123458 is a deficient number, since it is larger than the sum of its proper divisors (10561732).

21123458 is a wasteful number, since it uses less digits than its factorization.

21123458 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10561731.

The product of its digits is 1920, while the sum is 26.

The square root of 21123458 is about 4596.0263271657. The cubic root of 21123458 is about 276.4320143895.

The spelling of 21123458 in words is "twenty-one million, one hundred twenty-three thousand, four hundred fifty-eight".