21872781601 has 4 divisors (see below), whose sum is σ = 23861216304. Its totient is φ = 19884346900.

The previous prime is 21872781527. The next prime is 21872781613. The reversal of 21872781601 is 10618727812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21872781601 - 2⁷ = 21872781473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21872781901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 994217335 + ... + 994217356.

It is an arithmetic number, because the mean of its divisors is an integer number (5965304076).

Almost surely, 2^21872781601 is an apocalyptic number.

It is an amenable number.

21872781601 is a deficient number, since it is larger than the sum of its proper divisors (1988434703).

21872781601 is a wasteful number, since it uses less digits than its factorization.

21872781601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1988434702.

The product of its (nonzero) digits is 75264, while the sum is 43.

The spelling of 21872781601 in words is "twenty-one billion, eight hundred seventy-two million, seven hundred eighty-one thousand, six hundred one".