21360699409 has 9 divisors (see below), whose sum is σ = 24849350697. Its totient is φ = 18308294004.

The previous prime is 21360699401. The next prime is 21360699413. The reversal of 21360699409 is 90499606312.

The square root of 21360699409 is 146153.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21360699409 - 2³ = 21360699401 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21360699401) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1012632 + ... + 1033510.

Almost surely, 2^21360699409 is an apocalyptic number.

21360699409 is the 146153-rd square number.

21360699409 is the 73077-th centered octagonal number.

It is an amenable number.

21360699409 is a deficient number, since it is larger than the sum of its proper divisors (3488651288).

21360699409 is an frugal number, since it uses more digits than its factorization.

21360699409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41772 (or 20886 counting only the distinct ones).

The product of its (nonzero) digits is 629856, while the sum is 49.

Multiplying 21360699409 by its sum of digits (49), we get a square (1046674271041 = 1023071²).

21360699409 divided by its sum of digits (49) gives a square (435932641 = 20879²).

The spelling of 21360699409 in words is "twenty-one billion, three hundred sixty million, six hundred ninety-nine thousand, four hundred nine".