21677940509 has 4 divisors (see below), whose sum is σ = 21807748704. Its totient is φ = 21548132316.

The previous prime is 21677940499. The next prime is 21677940533. The reversal of 21677940509 is 90504977612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21677940509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21677040509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64903847 + ... + 64904180.

It is an arithmetic number, because the mean of its divisors is an integer number (5451937176).

Almost surely, 2^21677940509 is an apocalyptic number.

It is an amenable number.

21677940509 is a deficient number, since it is larger than the sum of its proper divisors (129808195).

21677940509 is a wasteful number, since it uses less digits than its factorization.

21677940509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129808194.

The product of its (nonzero) digits is 952560, while the sum is 50.

The spelling of 21677940509 in words is "twenty-one billion, six hundred seventy-seven million, nine hundred forty thousand, five hundred nine".