215451864 has 24 divisors (see below), whose sum is σ = 583515660. Its totient is φ = 71817264.

The previous prime is 215451853. The next prime is 215451869. The reversal of 215451864 is 468154512.

It is a happy number.

215451864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215451869) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1496122 + ... + 1496265.

Almost surely, 2^215451864 is an apocalyptic number.

215451864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

215451864 is an abundant number, since it is smaller than the sum of its proper divisors (368063796).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

215451864 is a wasteful number, since it uses less digits than its factorization.

215451864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2992399 (or 2992392 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The square root of 215451864 is about 14678.2786456723. The cubic root of 215451864 is about 599.4920367436.

It can be divided in two parts, 21545 and 1864, that added together give a square (23409 = 153²).

The spelling of 215451864 in words is "two hundred fifteen million, four hundred fifty-one thousand, eight hundred sixty-four".