402021091 has 4 divisors (see below), whose sum is σ = 404242384. Its totient is φ = 399799800.

The previous prime is 402021079. The next prime is 402021097. The reversal of 402021091 is 190120204.

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 402021091 - 2⁹ = 402020579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (402021097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1110375 + ... + 1110736.

It is an arithmetic number, because the mean of its divisors is an integer number (101060596).

Almost surely, 2^402021091 is an apocalyptic number.

402021091 is a deficient number, since it is larger than the sum of its proper divisors (2221293).

402021091 is a wasteful number, since it uses less digits than its factorization.

402021091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2221292.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 402021091 is about 20050.4636106001. The cubic root of 402021091 is about 738.0451759813.

Adding to 402021091 its reverse (190120204), we get a palindrome (592141295).

The spelling of 402021091 in words is "four hundred two million, twenty-one thousand, ninety-one".