21097556549 has 8 divisors (see below), whose sum is σ = 21216948480. Its totient is φ = 20978411616.

The previous prime is 21097556527. The next prime is 21097556561. The reversal of 21097556549 is 94565579012.

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 21097556549 - 2²⁴ = 21080779333 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21097556549.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21097556749) 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, 110924 + ... + 233450.

It is an arithmetic number, because the mean of its divisors is an integer number (2652118560).

Almost surely, 2^21097556549 is an apocalyptic number.

It is an amenable number.

21097556549 is a deficient number, since it is larger than the sum of its proper divisors (119391931).

21097556549 is a wasteful number, since it uses less digits than its factorization.

21097556549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123499.

The product of its (nonzero) digits is 3402000, while the sum is 53.

The spelling of 21097556549 in words is "twenty-one billion, ninety-seven million, five hundred fifty-six thousand, five hundred forty-nine".