61857993 has 4 divisors (see below), whose sum is σ = 82477328. Its totient is φ = 41238660.

The previous prime is 61857979. The next prime is 61857997. The reversal of 61857993 is 39975816.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-61857993 is a prime.

It is a super-2 number, since 2×61857993² = 7652822595976098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61857997) 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, 10309663 + ... + 10309668.

It is an arithmetic number, because the mean of its divisors is an integer number (20619332).

Almost surely, 2^61857993 is an apocalyptic number.

It is an amenable number.

61857993 is a deficient number, since it is larger than the sum of its proper divisors (20619335).

61857993 is a wasteful number, since it uses less digits than its factorization.

61857993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20619334.

The product of its digits is 408240, while the sum is 48.

The square root of 61857993 is about 7864.9852510987. The cubic root of 61857993 is about 395.4867534560.

The spelling of 61857993 in words is "sixty-one million, eight hundred fifty-seven thousand, nine hundred ninety-three".