21871258 has 4 divisors (see below), whose sum is σ = 32806890. Its totient is φ = 10935628.

The previous prime is 21871253. The next prime is 21871259. The reversal of 21871258 is 85217812.

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., 19333609 + 2537649 = 4397^2 + 1593^2 .

It is not an unprimeable number, because it can be changed into a prime (21871253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5467813 + ... + 5467816.

Almost surely, 2^21871258 is an apocalyptic number.

21871258 is a deficient number, since it is larger than the sum of its proper divisors (10935632).

21871258 is a wasteful number, since it uses less digits than its factorization.

21871258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10935631.

The product of its digits is 8960, while the sum is 34.

The square root of 21871258 is about 4676.6716797312. The cubic root of 21871258 is about 279.6562874337.

The spelling of 21871258 in words is "twenty-one million, eight hundred seventy-one thousand, two hundred fifty-eight".