19977 has 4 divisors (see below), whose sum is σ = 26640. Its totient is φ = 13316.

The previous prime is 19973. The next prime is 19979. The reversal of 19977 is 77991.

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, and also an emirpimes, since its reverse is a distinct semiprime: 77991 = 3 ⋅25997.

It is a cyclic number.

It is not a de Polignac number, because 19977 - 2² = 19973 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (19973) 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, 3327 + ... + 3332.

It is an arithmetic number, because the mean of its divisors is an integer number (6660).

2¹⁹⁹⁷⁷ is an apocalyptic number.

It is an amenable number.

19977 is a deficient number, since it is larger than the sum of its proper divisors (6663).

19977 is an equidigital number, since it uses as much as digits as its factorization.

19977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6662.

The product of its digits is 3969, while the sum is 33.

The square root of 19977 is about 141.3400155653. The cubic root of 19977 is about 27.1337669072.

It can be divided in two parts, 199 and 77, that added together give a triangular number (276 = T₂₃).

The spelling of 19977 in words is "nineteen thousand, nine hundred seventy-seven".