21555401346 has 20 divisors (see below), whose sum is σ = 48300066342. Its totient is φ = 7185133728.

The previous prime is 21555401341. The next prime is 21555401389. The reversal of 21555401346 is 64310455512.

21555401346 is a `hidden beast` number, since 21 + 55 + 540 + 1 + 3 + 46 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19750086225 + 1805315121 = 140535^2 + 42489^2 .

It is a super-2 number, since 2×21555401346² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21555401346.

It is not an unprimeable number, because it can be changed into a prime (21555401341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 66528855 + ... + 66529178.

Almost surely, 2^21555401346 is an apocalyptic number.

21555401346 is an abundant number, since it is smaller than the sum of its proper divisors (26744664996).

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

21555401346 is a wasteful number, since it uses less digits than its factorization.

21555401346 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133058047 (or 133058038 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 36.

Adding to 21555401346 its reverse (64310455512), we get a palindrome (85865856858).

The spelling of 21555401346 in words is "twenty-one billion, five hundred fifty-five million, four hundred one thousand, three hundred forty-six".