31172421 has 16 divisors (see below), whose sum is σ = 48513024. Its totient is φ = 17433264.

The previous prime is 31172413. The next prime is 31172431. The reversal of 31172421 is 12427113.

It is not a de Polignac number, because 31172421 - 2³ = 31172413 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31172411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14805 + ... + 16778.

It is an arithmetic number, because the mean of its divisors is an integer number (3032064).

Almost surely, 2^31172421 is an apocalyptic number.

It is an amenable number.

31172421 is a deficient number, since it is larger than the sum of its proper divisors (17340603).

31172421 is a wasteful number, since it uses less digits than its factorization.

31172421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31640.

The product of its digits is 336, while the sum is 21.

The square root of 31172421 is about 5583.2267552017. The cubic root of 31172421 is about 314.7193973792.

Adding to 31172421 its reverse (12427113), we get a palindrome (43599534).

The spelling of 31172421 in words is "thirty-one million, one hundred seventy-two thousand, four hundred twenty-one".