61431509 has 2 divisors, whose sum is σ = 61431510. Its totient is φ = 61431508.

The previous prime is 61431493. The next prime is 61431511. The reversal of 61431509 is 90513416.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60109009 + 1322500 = 7753^2 + 1150^2 .

It is a cyclic number.

It is not a de Polignac number, because 61431509 - 2⁴ = 61431493 is a prime.

Together with 61431511, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_3641942 and since 61431509 and 3641942 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61431529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30715754 + 30715755.

It is an arithmetic number, because the mean of its divisors is an integer number (30715755).

Almost surely, 2^61431509 is an apocalyptic number.

It is an amenable number.

61431509 is a deficient number, since it is larger than the sum of its proper divisors (1).

61431509 is an equidigital number, since it uses as much as digits as its factorization.

61431509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 61431509 is about 7837.8255275299. The cubic root of 61431509 is about 394.5757534454.

It can be divided in two parts, 614 and 31509, that added together give a palindrome (32123).

The spelling of 61431509 in words is "sixty-one million, four hundred thirty-one thousand, five hundred nine".