6211991 has 4 divisors (see below), whose sum is σ = 6257472. Its totient is φ = 6166512.

The previous prime is 6211981. The next prime is 6212009. The reversal of 6211991 is 1991126.

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

It is a cyclic number.

It is not a de Polignac number, because 6211991 - 2⁶ = 6211927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6211901) 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, 22535 + ... + 22808.

It is an arithmetic number, because the mean of its divisors is an integer number (1564368).

Almost surely, 2^6211991 is an apocalyptic number.

6211991 is a deficient number, since it is larger than the sum of its proper divisors (45481).

6211991 is a wasteful number, since it uses less digits than its factorization.

6211991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45480.

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

The square root of 6211991 is about 2492.3866072502. The cubic root of 6211991 is about 183.8274118117.

The spelling of 6211991 in words is "six million, two hundred eleven thousand, nine hundred ninety-one".