61209919 has 2 divisors, whose sum is σ = 61209920. Its totient is φ = 61209918.

The previous prime is 61209917. The next prime is 61209937. The reversal of 61209919 is 91990216.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61209919 - 2¹ = 61209917 is a prime.

It is a super-2 number, since 2×61209919² = 7493308367973122, which contains 22 as substring.

Together with 61209917, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_3629647 and since 61209919 and 3629647 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 (61209917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30604959 + 30604960.

It is an arithmetic number, because the mean of its divisors is an integer number (30604960).

Almost surely, 2^61209919 is an apocalyptic number.

61209919 is a deficient number, since it is larger than the sum of its proper divisors (1).

61209919 is an equidigital number, since it uses as much as digits as its factorization.

61209919 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 61209919 is about 7823.6768210350. The cubic root of 61209919 is about 394.1007562668.

It can be divided in two parts, 61209 and 919, that added together give a triangular number (62128 = T₃₅₂).

The spelling of 61209919 in words is "sixty-one million, two hundred nine thousand, nine hundred nineteen".