21786461646 has 16 divisors (see below), whose sum is σ = 43640696064. Its totient is φ = 7250858424.

The previous prime is 21786461629. The next prime is 21786461647. The reversal of 21786461646 is 64616468712.

It is a super-2 number, since 2×21786461646² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21786461647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2819686 + ... + 2827401.

It is an arithmetic number, because the mean of its divisors is an integer number (2727543504).

Almost surely, 2^21786461646 is an apocalyptic number.

21786461646 is an abundant number, since it is smaller than the sum of its proper divisors (21854234418).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21786461646 is a wasteful number, since it uses less digits than its factorization.

21786461646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5647735.

The product of its digits is 2322432, while the sum is 51.

The spelling of 21786461646 in words is "twenty-one billion, seven hundred eighty-six million, four hundred sixty-one thousand, six hundred forty-six".