20191961 has 4 divisors (see below), whose sum is σ = 20201424. Its totient is φ = 20182500.

The previous prime is 20191931. The next prime is 20191987. The reversal of 20191961 is 16919102.

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20191961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20191931) 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, 146 + ... + 6356.

It is an arithmetic number, because the mean of its divisors is an integer number (5050356).

Almost surely, 2^20191961 is an apocalyptic number.

It is an amenable number.

20191961 is a deficient number, since it is larger than the sum of its proper divisors (9463).

20191961 is an equidigital number, since it uses as much as digits as its factorization.

20191961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9462.

The product of its (nonzero) digits is 972, while the sum is 29.

The square root of 20191961 is about 4493.5465948402. The cubic root of 20191961 is about 272.3074351463.

The spelling of 20191961 in words is "twenty million, one hundred ninety-one thousand, nine hundred sixty-one".