61089991 has 2 divisors, whose sum is σ = 61089992. Its totient is φ = 61089990.

The previous prime is 61089967. The next prime is 61090009. The reversal of 61089991 is 19998016.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61089991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61089901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30544995 + 30544996.

It is an arithmetic number, because the mean of its divisors is an integer number (30544996).

Almost surely, 2^61089991 is an apocalyptic number.

61089991 is a deficient number, since it is larger than the sum of its proper divisors (1).

61089991 is an equidigital number, since it uses as much as digits as its factorization.

61089991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 61089991 is about 7816.0086361262. The cubic root of 61089991 is about 393.8432020573.

It can be divided in two parts, 610 and 89991, that added together give a square (90601 = 301²).

The spelling of 61089991 in words is "sixty-one million, eighty-nine thousand, nine hundred ninety-one".