31405381 has 4 divisors (see below), whose sum is σ = 35891872. Its totient is φ = 26918892.

The previous prime is 31405369. The next prime is 31405411. The reversal of 31405381 is 18350413.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 31405381 - 2⁵ = 31405349 is a prime.

It is a super-2 number, since 2×31405381² = 1972595911510322, 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 (31403381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2243235 + ... + 2243248.

It is an arithmetic number, because the mean of its divisors is an integer number (8972968).

Almost surely, 2^31405381 is an apocalyptic number.

31405381 is the 3236-th hex number.

It is an amenable number.

31405381 is a deficient number, since it is larger than the sum of its proper divisors (4486491).

31405381 is an equidigital number, since it uses as much as digits as its factorization.

31405381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4486490.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 31405381 is about 5604.0504101944. The cubic root of 31405381 is about 315.5014470629.

Adding to 31405381 its reverse (18350413), we get a palindrome (49755794).

The spelling of 31405381 in words is "thirty-one million, four hundred five thousand, three hundred eighty-one".