61721717 has 4 divisors (see below), whose sum is σ = 61998720. Its totient is φ = 61444716.

The previous prime is 61721711. The next prime is 61721749. The reversal of 61721717 is 71712716.

It is a happy number.

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 cyclic number.

It is not a de Polignac number, because 61721717 - 2¹⁴ = 61705333 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 (61721711) 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, 138167 + ... + 138612.

It is an arithmetic number, because the mean of its divisors is an integer number (15499680).

Almost surely, 2^61721717 is an apocalyptic number.

It is an amenable number.

61721717 is a deficient number, since it is larger than the sum of its proper divisors (277003).

61721717 is a wasteful number, since it uses less digits than its factorization.

61721717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277002.

The product of its digits is 4116, while the sum is 32.

The square root of 61721717 is about 7856.3170124429. The cubic root of 61721717 is about 395.1961147598.

Subtracting 61721717 from its reverse (71712716), we obtain a palindrome (9990999).

The spelling of 61721717 in words is "sixty-one million, seven hundred twenty-one thousand, seven hundred seventeen".