11901821 has 2 divisors, whose sum is σ = 11901822. Its totient is φ = 11901820.

The previous prime is 11901811. The next prime is 11901899. The reversal of 11901821 is 12810911.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7214596 + 4687225 = 2686^2 + 2165^2 .

It is a cyclic number.

It is not a de Polignac number, because 11901821 - 2¹⁴ = 11885437 is a prime.

It is a Chen prime.

It is equal to p₇₈₂₀₁₅ and since 11901821 and 782015 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11901811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5950910 + 5950911.

It is an arithmetic number, because the mean of its divisors is an integer number (5950911).

Almost surely, 2^11901821 is an apocalyptic number.

It is an amenable number.

11901821 is a deficient number, since it is larger than the sum of its proper divisors (1).

11901821 is an equidigital number, since it uses as much as digits as its factorization.

11901821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 11901821 is about 3449.9015927994. The cubic root of 11901821 is about 228.3167662810.

The spelling of 11901821 in words is "eleven million, nine hundred one thousand, eight hundred twenty-one".