20212691 has 2 divisors, whose sum is σ = 20212692. Its totient is φ = 20212690.

The previous prime is 20212667. The next prime is 20212721. The reversal of 20212691 is 19621202.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20212691 is a prime.

It is a super-2 number, since 2×20212691² = 817105754922962, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20212891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10106345 + 10106346.

It is an arithmetic number, because the mean of its divisors is an integer number (10106346).

Almost surely, 2^20212691 is an apocalyptic number.

20212691 is a deficient number, since it is larger than the sum of its proper divisors (1).

20212691 is an equidigital number, since it uses as much as digits as its factorization.

20212691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 20212691 is about 4495.8526443824. The cubic root of 20212691 is about 272.4005910718.

Adding to 20212691 its reverse (19621202), we get a palindrome (39833893).

The spelling of 20212691 in words is "twenty million, two hundred twelve thousand, six hundred ninety-one".