20151631 has 4 divisors (see below), whose sum is σ = 20340072. Its totient is φ = 19963192.

The previous prime is 20151619. The next prime is 20151667. The reversal of 20151631 is 13615102.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20151631 - 2⁷ = 20151503 is a prime.

It is a super-2 number, since 2×20151631² = 812176463920322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20151599 and 20151608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20151601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94060 + ... + 94273.

It is an arithmetic number, because the mean of its divisors is an integer number (5085018).

Almost surely, 2^20151631 is an apocalyptic number.

20151631 is a deficient number, since it is larger than the sum of its proper divisors (188441).

20151631 is a wasteful number, since it uses less digits than its factorization.

20151631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188440.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 20151631 is about 4489.0568051652. The cubic root of 20151631 is about 272.1260184157.

Adding to 20151631 its reverse (13615102), we get a palindrome (33766733).

The spelling of 20151631 in words is "twenty million, one hundred fifty-one thousand, six hundred thirty-one".