20918137651 has 4 divisors (see below), whose sum is σ = 20992579704. Its totient is φ = 20843695600.

The previous prime is 20918137649. The next prime is 20918137711. The reversal of 20918137651 is 15673181902.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20918137651 - 2¹ = 20918137649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20918137598 and 20918137607.

It is not an unprimeable number, because it can be changed into a prime (20918137151) 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, 37220605 + ... + 37221166.

It is an arithmetic number, because the mean of its divisors is an integer number (5248144926).

Almost surely, 2^20918137651 is an apocalyptic number.

20918137651 is a deficient number, since it is larger than the sum of its proper divisors (74442053).

20918137651 is an equidigital number, since it uses as much as digits as its factorization.

20918137651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74442052.

The product of its (nonzero) digits is 90720, while the sum is 43.

The spelling of 20918137651 in words is "twenty billion, nine hundred eighteen million, one hundred thirty-seven thousand, six hundred fifty-one".