21857391082 has 8 divisors (see below), whose sum is σ = 32788260036. Its totient is φ = 10927971072.

The previous prime is 21857391071. The next prime is 21857391121. The reversal of 21857391082 is 28019375812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17945013681 + 3912377401 = 133959^2 + 62549^2 .

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

It is a super-2 number, since 2×21857391082² (a number of 21 digits) contains 22 as substring.

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, 323703 + ... + 385354.

Almost surely, 2^21857391082 is an apocalyptic number.

21857391082 is a deficient number, since it is larger than the sum of its proper divisors (10930868954).

21857391082 is a wasteful number, since it uses less digits than its factorization.

21857391082 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 724472.

The product of its (nonzero) digits is 241920, while the sum is 46.

The spelling of 21857391082 in words is "twenty-one billion, eight hundred fifty-seven million, three hundred ninety-one thousand, eighty-two".