1640520947 has 8 divisors (see below), whose sum is σ = 1804305216. Its totient is φ = 1482106752.

The previous prime is 1640520943. The next prime is 1640520949. The reversal of 1640520947 is 7490250461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1640520947 - 2² = 1640520943 is a prime.

It is a super-4 number, since 4×1640520947⁴ (a number of 38 digits) contains 4444 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1640520947.

It is not an unprimeable number, because it can be changed into a prime (1640520941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1341878 + ... + 1343099.

It is an arithmetic number, because the mean of its divisors is an integer number (225538152).

Almost surely, 2^1640520947 is an apocalyptic number.

1640520947 is a deficient number, since it is larger than the sum of its proper divisors (163784269).

1640520947 is a wasteful number, since it uses less digits than its factorization.

1640520947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2685037.

The product of its (nonzero) digits is 60480, while the sum is 38.

The square root of 1640520947 is about 40503.3448865646. The cubic root of 1640520947 is about 1179.3985604460.

The spelling of 1640520947 in words is "one billion, six hundred forty million, five hundred twenty thousand, nine hundred forty-seven".