61511621 has 2 divisors, whose sum is σ = 61511622. Its totient is φ = 61511620.

The previous prime is 61511573. The next prime is 61511623. The reversal of 61511621 is 12611516.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36120100 + 25391521 = 6010^2 + 5039^2 .

It is a cyclic number.

It is not a de Polignac number, because 61511621 - 2⁶ = 61511557 is a prime.

Together with 61511623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61511623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30755810 + 30755811.

It is an arithmetic number, because the mean of its divisors is an integer number (30755811).

Almost surely, 2^61511621 is an apocalyptic number.

It is an amenable number.

61511621 is a deficient number, since it is larger than the sum of its proper divisors (1).

61511621 is an equidigital number, since it uses as much as digits as its factorization.

61511621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 23.

The square root of 61511621 is about 7842.9344635793. The cubic root of 61511621 is about 394.7471992414.

The spelling of 61511621 in words is "sixty-one million, five hundred eleven thousand, six hundred twenty-one".