21861499671 has 24 divisors (see below), whose sum is σ = 35599386480. Its totient is φ = 13249391760.

The previous prime is 21861499663. The next prime is 21861499717. The reversal of 21861499671 is 17699416812.

21861499671 is a `hidden beast` number, since 2 + 1 + 86 + 1 + 499 + 6 + 71 = 666.

It is not a de Polignac number, because 21861499671 - 2³ = 21861499663 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861499601) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3342540 + ... + 3349073.

It is an arithmetic number, because the mean of its divisors is an integer number (1483307770).

Almost surely, 2^21861499671 is an apocalyptic number.

21861499671 is a deficient number, since it is larger than the sum of its proper divisors (13737886809).

21861499671 is a wasteful number, since it uses less digits than its factorization.

21861499671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6691644 (or 6691627 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 54.

The spelling of 21861499671 in words is "twenty-one billion, eight hundred sixty-one million, four hundred ninety-nine thousand, six hundred seventy-one".