20891213 has 8 divisors (see below), whose sum is σ = 24203328. Its totient is φ = 17661024.

The previous prime is 20891209. The next prime is 20891239. The reversal of 20891213 is 31219802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20891213 - 2² = 20891209 is a prime.

It is a super-2 number, since 2×20891213² = 872885561222738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20891293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19931 + ... + 20952.

It is an arithmetic number, because the mean of its divisors is an integer number (3025416).

Almost surely, 2^20891213 is an apocalyptic number.

It is an amenable number.

20891213 is a deficient number, since it is larger than the sum of its proper divisors (3312115).

20891213 is an equidigital number, since it uses as much as digits as its factorization.

20891213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40963.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 20891213 is about 4570.6906480312. The cubic root of 20891213 is about 275.4151877211.

The spelling of 20891213 in words is "twenty million, eight hundred ninety-one thousand, two hundred thirteen".