61639951 has 4 divisors (see below), whose sum is σ = 62650504. Its totient is φ = 60629400.

The previous prime is 61639939. The next prime is 61639957. The reversal of 61639951 is 15993616.

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

It is a cyclic number.

It is not a de Polignac number, because 61639951 - 2²¹ = 59542799 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 (61639957) 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, 505185 + ... + 505306.

It is an arithmetic number, because the mean of its divisors is an integer number (15662626).

Almost surely, 2^61639951 is an apocalyptic number.

61639951 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

61639951 is a deficient number, since it is larger than the sum of its proper divisors (1010553).

61639951 is a wasteful number, since it uses less digits than its factorization.

61639951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010552.

The product of its digits is 43740, while the sum is 40.

The square root of 61639951 is about 7851.1114499796. Note that the first 3 decimals coincide. The cubic root of 61639951 is about 395.0215252917.

The spelling of 61639951 in words is "sixty-one million, six hundred thirty-nine thousand, nine hundred fifty-one".