1001215551 has 8 divisors (see below), whose sum is σ = 1525661824. Its totient is φ = 572123160.

The previous prime is 1001215547. The next prime is 1001215559. The reversal of 1001215551 is 1555121001.

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

It is not a de Polignac number, because 1001215551 - 2² = 1001215547 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 47676931 = 1001215551 / (1 + 0 + 0 + 1 + 2 + 1 + 5 + 5 + 5 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001215559) 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, 23838445 + ... + 23838486.

It is an arithmetic number, because the mean of its divisors is an integer number (190707728).

Almost surely, 2^1001215551 is an apocalyptic number.

1001215551 is a deficient number, since it is larger than the sum of its proper divisors (524446273).

1001215551 is an equidigital number, since it uses as much as digits as its factorization.

1001215551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47676941.

The product of its (nonzero) digits is 250, while the sum is 21.

The square root of 1001215551 is about 31641.9903135059. The cubic root of 1001215551 is about 1000.4050196036.

Adding to 1001215551 its reverse (1555121001), we get a palindrome (2556336552).

The spelling of 1001215551 in words is "one billion, one million, two hundred fifteen thousand, five hundred fifty-one".