20977891 has 8 divisors (see below), whose sum is σ = 23075568. Its totient is φ = 19069600.

The previous prime is 20977889. The next prime is 20977951. The reversal of 20977891 is 19877902.

It is a happy number.

It is not a de Polignac number, because 20977891 - 2¹ = 20977889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20977811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6550 + ... + 9211.

It is an arithmetic number, because the mean of its divisors is an integer number (2884446).

Almost surely, 2^20977891 is an apocalyptic number.

20977891 is a deficient number, since it is larger than the sum of its proper divisors (2097677).

20977891 is an equidigital number, since it uses as much as digits as its factorization.

20977891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15794 (or 15772 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 20977891 is about 4580.1627700334. The cubic root of 20977891 is about 275.7955629187.

The spelling of 20977891 in words is "twenty million, nine hundred seventy-seven thousand, eight hundred ninety-one".