21871970 has 8 divisors (see below), whose sum is σ = 39369564. Its totient is φ = 8748784.

The previous prime is 21871961. The next prime is 21871991. The reversal of 21871970 is 7917812.

It can be written as a sum of positive squares in 2 ways, for example, as 21520321 + 351649 = 4639^2 + 593^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21871970.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093589 + ... + 1093608.

Almost surely, 2^21871970 is an apocalyptic number.

21871970 is a deficient number, since it is larger than the sum of its proper divisors (17497594).

21871970 is a wasteful number, since it uses less digits than its factorization.

21871970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187204.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21871970 is about 4676.7478016245. The cubic root of 21871970 is about 279.6593220575.

The spelling of 21871970 in words is "twenty-one million, eight hundred seventy-one thousand, nine hundred seventy".