31402561 has 2 divisors, whose sum is σ = 31402562. Its totient is φ = 31402560.

The previous prime is 31402549. The next prime is 31402577. The reversal of 31402561 is 16520413.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26204161 + 5198400 = 5119^2 + 2280^2 .

It is a cyclic number.

It is not a de Polignac number, because 31402561 - 2¹³ = 31394369 is a prime.

It is a super-2 number, since 2×31402561² = 1972241674717442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31409561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15701280 + 15701281.

It is an arithmetic number, because the mean of its divisors is an integer number (15701281).

Almost surely, 2^31402561 is an apocalyptic number.

It is an amenable number.

31402561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31402561 is an equidigital number, since it uses as much as digits as its factorization.

31402561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 31402561 is about 5603.7988008136. The cubic root of 31402561 is about 315.4920034508.

Adding to 31402561 its reverse (16520413), we get a palindrome (47922974).

The spelling of 31402561 in words is "thirty-one million, four hundred two thousand, five hundred sixty-one".