21349196581 has 8 divisors (see below), whose sum is σ = 23215979160. Its totient is φ = 19550297088.

The previous prime is 21349196563. The next prime is 21349196587. The reversal of 21349196581 is 18569194312.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9591264225 + 11757932356 = 97935^2 + 108434^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21349196581 - 2¹⁵ = 21349163813 is a prime.

It is a super-2 number, since 2×21349196581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349196587) 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, 16970116 + ... + 16971373.

It is an arithmetic number, because the mean of its divisors is an integer number (2901997395).

Almost surely, 2^21349196581 is an apocalyptic number.

It is an amenable number.

21349196581 is a deficient number, since it is larger than the sum of its proper divisors (1866782579).

21349196581 is a wasteful number, since it uses less digits than its factorization.

21349196581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33941543.

The product of its digits is 466560, while the sum is 49.

The spelling of 21349196581 in words is "twenty-one billion, three hundred forty-nine million, one hundred ninety-six thousand, five hundred eighty-one".