31511242421 has 4 divisors (see below), whose sum is σ = 32527734144. Its totient is φ = 30494750700.

The previous prime is 31511242387. The next prime is 31511242423. The reversal of 31511242421 is 12424211513.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31511242421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31511242423) 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, 508245815 + ... + 508245876.

It is an arithmetic number, because the mean of its divisors is an integer number (8131933536).

Almost surely, 2^31511242421 is an apocalyptic number.

31511242421 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31511242421 is a deficient number, since it is larger than the sum of its proper divisors (1016491723).

31511242421 is a wasteful number, since it uses less digits than its factorization.

31511242421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1016491722.

The product of its digits is 1920, while the sum is 26.

Adding to 31511242421 its reverse (12424211513), we get a palindrome (43935453934).

The spelling of 31511242421 in words is "thirty-one billion, five hundred eleven million, two hundred forty-two thousand, four hundred twenty-one".