210400921 has 2 divisors, whose sum is σ = 210400922. Its totient is φ = 210400920.

The previous prime is 210400873. The next prime is 210400943. The reversal of 210400921 is 129004012.

210400921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 191434896 + 18966025 = 13836^2 + 4355^2 .

It is a cyclic number.

It is not a de Polignac number, because 210400921 - 2⁷ = 210400793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (210400991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105200460 + 105200461.

It is an arithmetic number, because the mean of its divisors is an integer number (105200461).

Almost surely, 2^210400921 is an apocalyptic number.

It is an amenable number.

210400921 is a deficient number, since it is larger than the sum of its proper divisors (1).

210400921 is an equidigital number, since it uses as much as digits as its factorization.

210400921 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 19.

The square root of 210400921 is about 14505.2032388381. The cubic root of 210400921 is about 594.7702156275.

Adding to 210400921 its reverse (129004012), we get a palindrome (339404933).

The spelling of 210400921 in words is "two hundred ten million, four hundred thousand, nine hundred twenty-one".