61857391 has 4 divisors (see below), whose sum is σ = 62425000. Its totient is φ = 61289784.

The previous prime is 61857329. The next prime is 61857421. The reversal of 61857391 is 19375816.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61857391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61857491) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 283641 + ... + 283858.

It is an arithmetic number, because the mean of its divisors is an integer number (15606250).

Almost surely, 2^61857391 is an apocalyptic number.

61857391 is a deficient number, since it is larger than the sum of its proper divisors (567609).

61857391 is a wasteful number, since it uses less digits than its factorization.

61857391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567608.

The product of its digits is 45360, while the sum is 40.

The square root of 61857391 is about 7864.9469801137. The cubic root of 61857391 is about 395.4854704970.

The spelling of 61857391 in words is "sixty-one million, eight hundred fifty-seven thousand, three hundred ninety-one".