20951276891 has 4 divisors (see below), whose sum is σ = 21067029984. Its totient is φ = 20835523800.

The previous prime is 20951276881. The next prime is 20951276917. The reversal of 20951276891 is 19867215902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19867215902 = 2 ⋅9933607951.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20951276891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20951276831) 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, 57876275 + ... + 57876636.

It is an arithmetic number, because the mean of its divisors is an integer number (5266757496).

Almost surely, 2^20951276891 is an apocalyptic number.

20951276891 is a deficient number, since it is larger than the sum of its proper divisors (115753093).

20951276891 is a wasteful number, since it uses less digits than its factorization.

20951276891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115753092.

The product of its (nonzero) digits is 544320, while the sum is 50.

The spelling of 20951276891 in words is "twenty billion, nine hundred fifty-one million, two hundred seventy-six thousand, eight hundred ninety-one".