1021689987 has 8 divisors (see below), whose sum is σ = 1442385936. Its totient is φ = 641060352.

The previous prime is 1021689973. The next prime is 1021689989. The reversal of 1021689987 is 7899861201.

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

It is not a de Polignac number, because 1021689987 - 2¹⁶ = 1021624451 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 20033137 = 1021689987 / (1 + 0 + 2 + 1 + 6 + 8 + 9 + 9 + 8 + 7).

It is not an unprimeable number, because it can be changed into a prime (1021689989) 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, 10016518 + ... + 10016619.

It is an arithmetic number, because the mean of its divisors is an integer number (180298242).

Almost surely, 2^1021689987 is an apocalyptic number.

1021689987 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

1021689987 is a deficient number, since it is larger than the sum of its proper divisors (420695949).

1021689987 is a wasteful number, since it uses less digits than its factorization.

1021689987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20033157.

The product of its (nonzero) digits is 435456, while the sum is 51.

The square root of 1021689987 is about 31963.8856680473. The cubic root of 1021689987 is about 1007.1783437509.

The spelling of 1021689987 in words is "one billion, twenty-one million, six hundred eighty-nine thousand, nine hundred eighty-seven".