642156609 has 16 divisors (see below), whose sum is σ = 870322752. Its totient is φ = 421067328.

The previous prime is 642156607. The next prime is 642156611. The reversal of 642156609 is 906651246.

It is an interprime number because it is at equal distance from previous prime (642156607) and next prime (642156611).

It is not a de Polignac number, because 642156609 - 2¹ = 642156607 is a prime.

It is a super-2 number, since 2×642156609² = 824730220964757762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (642156601) 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, 153307 + ... + 157439.

It is an arithmetic number, because the mean of its divisors is an integer number (54395172).

Almost surely, 2^642156609 is an apocalyptic number.

It is an amenable number.

642156609 is a deficient number, since it is larger than the sum of its proper divisors (228166143).

642156609 is a wasteful number, since it uses less digits than its factorization.

642156609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4976.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 642156609 is about 25340.8091622979. The cubic root of 642156609 is about 862.7407643751.

The spelling of 642156609 in words is "six hundred forty-two million, one hundred fifty-six thousand, six hundred nine".