31257421 has 4 divisors (see below), whose sum is σ = 33661852. Its totient is φ = 28852992.

The previous prime is 31257419. The next prime is 31257427. The reversal of 31257421 is 12475213.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11356900 + 19900521 = 3370^2 + 4461^2 .

It is a cyclic number.

It is not a de Polignac number, because 31257421 - 2¹ = 31257419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31257427) 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, 1202196 + ... + 1202221.

It is an arithmetic number, because the mean of its divisors is an integer number (8415463).

Almost surely, 2^31257421 is an apocalyptic number.

It is an amenable number.

31257421 is a deficient number, since it is larger than the sum of its proper divisors (2404431).

31257421 is a wasteful number, since it uses less digits than its factorization.

31257421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2404430.

The product of its digits is 1680, while the sum is 25.

The square root of 31257421 is about 5590.8336587668. The cubic root of 31257421 is about 315.0051934980.

The spelling of 31257421 in words is "thirty-one million, two hundred fifty-seven thousand, four hundred twenty-one".