20979232787 has 4 divisors (see below), whose sum is σ = 20989761240. Its totient is φ = 20968704336.

The previous prime is 20979232783. The next prime is 20979232801. The reversal of 20979232787 is 78723297902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78723297902 = 2 ⋅39361648951.

It is a cyclic number.

It is not a de Polignac number, because 20979232787 - 2² = 20979232783 is a prime.

It is a super-2 number, since 2×20979232787² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20979232783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5261237 + ... + 5265222.

It is an arithmetic number, because the mean of its divisors is an integer number (5247440310).

Almost surely, 2^20979232787 is an apocalyptic number.

20979232787 is a deficient number, since it is larger than the sum of its proper divisors (10528453).

20979232787 is a wasteful number, since it uses less digits than its factorization.

20979232787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10528452.

The product of its (nonzero) digits is 5334336, while the sum is 56.

The spelling of 20979232787 in words is "twenty billion, nine hundred seventy-nine million, two hundred thirty-two thousand, seven hundred eighty-seven".