151620821 has 4 divisors (see below), whose sum is σ = 165404544. Its totient is φ = 137837100.

The previous prime is 151620811. The next prime is 151620823. The reversal of 151620821 is 128026151.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 128026151 = 11 ⋅11638741.

It is a cyclic number.

It is not a de Polignac number, because 151620821 - 2¹⁸ = 151358677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (151620823) 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, 6891845 + ... + 6891866.

It is an arithmetic number, because the mean of its divisors is an integer number (41351136).

Almost surely, 2^151620821 is an apocalyptic number.

151620821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

151620821 is a deficient number, since it is larger than the sum of its proper divisors (13783723).

151620821 is a wasteful number, since it uses less digits than its factorization.

151620821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13783722.

The product of its (nonzero) digits is 960, while the sum is 26.

The square root of 151620821 is about 12313.4406645746. The cubic root of 151620821 is about 533.2361874710.

Adding to 151620821 its reverse (128026151), we get a palindrome (279646972).

The spelling of 151620821 in words is "one hundred fifty-one million, six hundred twenty thousand, eight hundred twenty-one".