1661722917 has 16 divisors (see below), whose sum is σ = 2268592128. Its totient is φ = 1081367280.

The previous prime is 1661722913. The next prime is 1661722921. The reversal of 1661722917 is 7192271661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1661722913) and next prime (1661722921).

It is not a de Polignac number, because 1661722917 - 2² = 1661722913 is a prime.

It is a super-2 number, since 2×1661722917² = 5522646105765977778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661722913) 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, 273442 + ... + 279452.

It is an arithmetic number, because the mean of its divisors is an integer number (141787008).

Almost surely, 2^1661722917 is an apocalyptic number.

It is an amenable number.

1661722917 is a deficient number, since it is larger than the sum of its proper divisors (606869211).

1661722917 is a wasteful number, since it uses less digits than its factorization.

1661722917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8200.

The product of its digits is 63504, while the sum is 42.

The square root of 1661722917 is about 40764.2357588119. The cubic root of 1661722917 is about 1184.4576478059.

The spelling of 1661722917 in words is "one billion, six hundred sixty-one million, seven hundred twenty-two thousand, nine hundred seventeen".