61991109 has 16 divisors (see below), whose sum is σ = 92016000. Its totient is φ = 41247648.

The previous prime is 61991107. The next prime is 61991117. The reversal of 61991109 is 90119916.

It is not a de Polignac number, because 61991109 - 2¹ = 61991107 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61991107) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14257 + ... + 18089.

It is an arithmetic number, because the mean of its divisors is an integer number (5751000).

Almost surely, 2^61991109 is an apocalyptic number.

It is an amenable number.

61991109 is a deficient number, since it is larger than the sum of its proper divisors (30024891).

61991109 is a wasteful number, since it uses less digits than its factorization.

61991109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4441 (or 4435 counting only the distinct ones).

The product of its (nonzero) digits is 4374, while the sum is 36.

The square root of 61991109 is about 7873.4432747052. The cubic root of 61991109 is about 395.7702409161.

The spelling of 61991109 in words is "sixty-one million, nine hundred ninety-one thousand, one hundred nine".