21959639551 has 16 divisors (see below), whose sum is σ = 24660082368. Its totient is φ = 19445184000.

The previous prime is 21959639549. The next prime is 21959639567. The reversal of 21959639551 is 15593695912.

It is a cyclic number.

It is not a de Polignac number, because 21959639551 - 2¹ = 21959639549 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21959639492 and 21959639501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21959639951) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 436500 + ... + 484201.

It is an arithmetic number, because the mean of its divisors is an integer number (1541255148).

Almost surely, 2^21959639551 is an apocalyptic number.

21959639551 is a deficient number, since it is larger than the sum of its proper divisors (2700442817).

21959639551 is a wasteful number, since it uses less digits than its factorization.

21959639551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 920802.

The product of its digits is 3280500, while the sum is 55.

The spelling of 21959639551 in words is "twenty-one billion, nine hundred fifty-nine million, six hundred thirty-nine thousand, five hundred fifty-one".