31381920 has 288 divisors, whose sum is σ = 119508480. Its totient is φ = 7464960.

The previous prime is 31381907. The next prime is 31381927. The reversal of 31381920 is 2918313.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31381927) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 848142 + ... + 848178.

It is an arithmetic number, because the mean of its divisors is an integer number (414960).

Almost surely, 2^31381920 is an apocalyptic number.

31381920 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31381920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59754240).

31381920 is an abundant number, since it is smaller than the sum of its proper divisors (88126560).

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

31381920 is a wasteful number, since it uses less digits than its factorization.

31381920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 31381920 is about 5601.9568009759. The cubic root of 31381920 is about 315.4228636783.

It can be divided in two parts, 3 and 1381920, that multiplied together give a triangular number (4145760 = T₂₈₇₉).

The spelling of 31381920 in words is "thirty-one million, three hundred eighty-one thousand, nine hundred twenty".