20977961 has 4 divisors (see below), whose sum is σ = 21321924. Its totient is φ = 20634000.

The previous prime is 20977951. The next prime is 20977967. The reversal of 20977961 is 16977902.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3705625 + 17272336 = 1925^2 + 4156^2 .

It is a cyclic number.

It is not a de Polignac number, because 20977961 - 2¹⁰ = 20976937 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20977967) 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, 171890 + ... + 172011.

It is an arithmetic number, because the mean of its divisors is an integer number (5330481).

Almost surely, 2^20977961 is an apocalyptic number.

It is an amenable number.

20977961 is a deficient number, since it is larger than the sum of its proper divisors (343963).

20977961 is an equidigital number, since it uses as much as digits as its factorization.

20977961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343962.

The product of its (nonzero) digits is 47628, while the sum is 41.

The square root of 20977961 is about 4580.1704116768. The cubic root of 20977961 is about 275.7958696808.

The spelling of 20977961 in words is "twenty million, nine hundred seventy-seven thousand, nine hundred sixty-one".