402991 has 2 divisors, whose sum is σ = 402992. Its totient is φ = 402990.

The previous prime is 402949. The next prime is 403001. The reversal of 402991 is 199204.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 402991 - 2⁷ = 402863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201495 + 201496.

It is an arithmetic number, because the mean of its divisors is an integer number (201496).

2⁴⁰²⁹⁹¹ is an apocalyptic number.

402991 is a deficient number, since it is larger than the sum of its proper divisors (1).

402991 is an equidigital number, since it uses as much as digits as its factorization.

402991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 402991 is about 634.8157212924. The cubic root of 402991 is about 73.8638230901.

The spelling of 402991 in words is "four hundred two thousand, nine hundred ninety-one".