31390020 has 36 divisors (see below), whose sum is σ = 95216940. Its totient is φ = 8370624.

The previous prime is 31390013. The next prime is 31390027. The reversal of 31390020 is 2009313.

It is an interprime number because it is at equal distance from previous prime (31390013) and next prime (31390027).

It can be written as a sum of positive squares in 2 ways, for example, as 9036036 + 22353984 = 3006^2 + 4728^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31389975 and 31390002.

It is not an unprimeable number, because it can be changed into a prime (31390027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 87015 + ... + 87374.

It is an arithmetic number, because the mean of its divisors is an integer number (2644915).

Almost surely, 2^31390020 is an apocalyptic number.

31390020 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31390020 is an abundant number, since it is smaller than the sum of its proper divisors (63826920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31390020 is a wasteful number, since it uses less digits than its factorization.

31390020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174404 (or 174399 counting only the distinct ones).

The product of its (nonzero) digits is 162, while the sum is 18.

The square root of 31390020 is about 5602.6797159931. The cubic root of 31390020 is about 315.4499993179.

Adding to 31390020 its reverse (2009313), we get a palindrome (33399333).

The spelling of 31390020 in words is "thirty-one million, three hundred ninety thousand, twenty".